Hillstone E-3000 SeriesNext-Generation FirewallE3662 / E3668 / E3960 / E3965 / E3968The Hillstone E-3000 Series Next Generation Firewall (NGFW) is design for the specific function of security and provide comprehensive and granular visibility and control of applications. It can identify and prevent potential threats associated with high-risk applications while providing poli-cy-based control over applications, users, and user-groups. Policies can be defined that guarantee bandwidth to mission-critical applications while restricting or blocking unauthorized or malicious applications. The Hillstone E-3000 Series NGFW incorporates comprehensive network security and advanced firewall features, provides superior price performance, excellent energy efficiency, and comprehensive threat prevention capability.Product HighlightGranular Application Identification and ControlThe Hillstone E-3000 Series NGFW is optimized for con-tent analysis of Layer 7 applications, providing fine-grained control of web applications regardless of port, protocol, or evasive action. It can identify and prevent potential threats associated with high-risk applications while providing poli-cy-based control over applications, users, and user-groups. Security Policies can be defined that guarantee bandwidth to mission-critical applications while restricting or blocking unauthorized or malicious applications. Comprehensive Threat Detection and PreventionThe Hillstone E-3000 Series NGFW provides real-time protec-tion for applications from network attacks including viruses, spyware, worms, botnets, ARP spoofing, DoS/DDoS, Tro-jans, buffer overflows, and SQL injections. It incorporates a unified threat detection engine that shares packet details with multiple security engines (AD, IPS, URL filtering, Anti-Virus, Sandbox etc.), which significantly enhances the protectionefficiency and reduces network latency.Network Services• Dynamic routing (OSPF, BGP, RIPv2)• Static and Policy routing• Route controlled by application• Built-in DHCP, NTP, DNS Server and DNS proxy • Tap mode – connects to SPAN port• Interface modes: sniffer, port aggregated, loopback, VLANS (802.1Q and Trunking)• L2/L3 switching & routing• Virtual wire (Layer 1) transparent inline deploymentFirewall• Operating modes: NAT/route, transparent (bridge), and mixed mode• Policy objects: predefined, custom, and object grouping• Security policy based on application, role and geo-location• Application Level Gateways and session support: MSRCP, PPTP, RAS, RSH, SIP, FTP, TFTP, HTTP, dcerpc, dns-tcp, dns-udp, H.245 0, H.245 1, H.323• NAT and ALG support: NAT46, NAT64, NAT444, SNAT, DNAT, PAT, Full Cone NAT, STUN• NAT configuration: per policy and central NAT table• VoIP: SIP/H.323/SCCP NAT traversal, RTP pin holing• Global policy management view• Security policy redundancy inspection, policy group, policy configuration rollback• Policy Assistant for easy detailed policy deployment• Policy analyzing and invalid policy cleanup• Comprehensive DNS policy• Schedules: one-time and recurringIntrusion Prevention• Protocol anomaly detection, rate-based detection, custom signatures, manual, automatic push or pull signature updates, integrated threat encyclo-pedia• IPS Actions: default, monitor, block, reset (attackers IP or victim IP, incoming interface) with expiry time• Packet logging option• Filter Based Selection: severity, target, OS, appli-cation or protocol• IP exemption from specific IPS signatures• IDS sniffer mode• IPv4 and IPv6 rate based DoS protection with threshold settings against TCP Syn flood, TCP/ UDP/SCTP port scan, ICMP sweep, TCP/UDP/ SCIP/ICMP session flooding (source/destination)• Active bypass with bypass interfaces• Predefined prevention configurationAnti-Virus• Manual, automatic push or pull signature updates • Flow-based Antivirus: protocols include HTTP, SMTP, POP3, IMAP, FTP/SFTP• Compressed file virus scanningAttack Defense• Abnormal protocol attack defense• Anti-DoS/DDoS, including SYN Flood, UDP Flood, DNS Query Flood defense, TCP fragment, ICMP fragment, etc.• ARP attack defenseURL Filtering• Flow-based web filtering inspection• Manually defined web filtering based on URL, webcontent and MIME header• Dynamic web filtering with cloud-based real-timecategorization database: over 140 million URLswith 64 categories (8 of which are security related)• Additional web filtering features:- Filter Java Applet, ActiveX or cookie- Block HTTP Post- Log search keywords- Exempt scanning encrypted connections oncertain categories for privacy• Web filtering profile override: allows administratorto temporarily assign different profiles to user/group/IP• Web filter local categories and category ratingoverride• Support multi-languageCloud-Sandbox• Upload malicious files to cloud sandbox foranalysis• Support protocols including HTTP/HTTPS, POP3,IMAP, SMTP and FTP• Support file types including PE,ZIP, RAR, Office,PDF, APK, JAR and SWF• File transfer direction and file size control• Provide complete behavior analysis report formalicious files• Global threat intelligence sharing, real-time threatblocking• Support detection only mode without uploadingfilesBotnet C&C Prevention• Discover intranet botnet host by monitoring C&Cconnections and block further advanced threatssuch as botnet and ransomware• Regularly update the botnet server addresses• Prevention for C&C IP and domain• Support TCP, HTTP, and DNS traffic detection• IP and domain whitelistsIP Reputation• Identify and filter traffic from risky IPs such asbotnet hosts, spammers, Tor nodes, breachedhosts, and brute force attacks• Logging, dropping packets, or blocking fordifferent types of risky IP traffic• Periodical IP reputation signature databaseupgradeSSL Decryption• Application identification for SSL encrypted traffic• IPS enablement for SSL encrypted traffic• AV enablement for SSL encrypted traffic• URL filter for SSL encrypted traffic• SSL Encrypted traffic whitelist• SSL proxy offload modeEndpoint Identification and Control• Support to identify endpoint IP, endpoint quantity,on-line time, off-line time, and on-line duration• Support 10 operation systems including Windows,iOS, Android, etc.• Support query based on IP, endpoint quantity,control policy and status etc.• Support the identification of accessed endpointsquantity across layer 3, logging and interferenceon overrun IP• Redirect page display after custom interferenceoperation• Supports blocking operations on overrun IPData Security• File transfer control based on file type, size andname• File protocol identification, including HTTP, FTP,SMTP and POP3• File signature and suffix identification for over 100file types• Content filtering for HTTP-GET, HTTP-POST, FTPand SMTP protocols• IM identification and network behavior audit• Filter files transmitted by HTTPS using SSL ProxyApplication Control• Over 3,000 applications that can be filtered byname, category, subcategory, technology and risk• Each application contains a description, riskfactors, dependencies, typical ports used, andURLs for additional reference• Actions: block, reset session, monitor, trafficshaping• Identify and control cloud applications in the cloud• Provide multi-dimensional monitoring andstatistics for cloud applications, including riskcategory and characteristicsQuality of Service (QoS)• Max/guaranteed bandwidth tunnels or IP/userbasis• Tunnel allocation based on security domain,interface, address, user/user group, server/servergroup, application/app group, TOS, VLAN• Bandwidth allocated by time, priority, or equalbandwidth sharing• Type of Service (TOS) and Differentiated Services(DiffServ) support• Prioritized allocation of remaining bandwidth• Maximum concurrent connections per IP• Bandwidth allocation based on URL category• Bandwidth limit by delaying access for user or IP• Automatic expiration cleanup and manual cleanupof user used trafficServer Load Balancing• Weighted hashing, weighted least-connection, andweighted round-robin• Session protection, session persistence andsession status monitoring• Server health check, session monitoring andsession protectionLink Load Balancing• Bi-directional link load balancing• Outbound link load balancing includes policybased routing, ECMP and weighted, embeddedISP routing and dynamic detection• Inbound link load balancing supports SmartDNSand dynamic detection• Automatic link switching based on bandwidth,latency, jitter, connectivity, application etc.• Link health inspection with ARP, PING, and DNSFeaturesFeatures (Continued)VPN• IPSec VPN- IPSEC Phase 1 mode: aggressive and main ID protection mode- Peer acceptance options: any ID, specific ID, ID in dialup user group- Supports IKEv1 and IKEv2 (RFC 4306)- Authentication method: certificate andpre-shared key- IKE mode configuration support (as server orclient)- DHCP over IPSEC- Configurable IKE encryption key expiry, NATtraversal keep alive frequency- Phase 1/Phase 2 Proposal encryption: DES,3DES, AES128, AES192, AES256- Phase 1/Phase 2 Proposal authentication:MD5, SHA1, SHA256, SHA384,SHA512- Phase 1/Phase 2 Diffie-Hellman support: 1,2,5 - XAuth as server mode and for dialup users- Dead peer detection- Replay detection- Autokey keep-alive for Phase 2 SA• IPSEC VPN realm support: allows multiple custom SSL VPN logins associated with user groups (URL paths, design)• IPSEC VPN configuration options: route-based or policy based• IPSEC VPN deployment modes: gateway-to-gateway, full mesh, hub-and-spoke, redundant tunnel, VPN termination in transparent mode • One time login prevents concurrent logins with the same username• SSL portal concurrent users limiting• SSL VPN port forwarding module encrypts client data and sends the data to the application server • Supports clients that run iOS, Android, and Windows XP/Vista including 64-bit Windows OS • Host integrity checking and OS checking prior to SSL tunnel connections• MAC host check per portal• Cache cleaning option prior to ending SSL VPN session• L2TP client and server mode, L2TP over IPSEC, and GRE over IPSEC• View and manage IPSEC and SSL VPN connec-tions• PnPVPNIPv6• Management over IPv6, IPv6 logging and HA • IPv6 tunneling, DNS64/NAT64 etc• IPv6 routing including static routing, policy routing, ISIS, RIPng, OSPFv3 and BGP4+• IPS, Application identification, URL filtering,Anti-Virus, Access control, ND attack defense,iQoS• Track address detectionVSYS• System resource allocation to each VSYS• CPU virtualization• Non-root VSYS support firewall, IPSec VPN, SSLVPN, IPS, URL filtering• VSYS monitoring and statisticHigh Availability• Redundant heartbeat interfaces• Active/Active and Active/Passive mode• Standalone session synchronization• HA reserved management interface• Failover:- Port, local & remote link monitoring- Stateful failover- Sub-second failover- Failure notification• Deployment options:- HA with link aggregation- Full mesh HA- Geographically dispersed HATwin-mode HA (not available on E3662, E3668)• High availability mode among multiple devices• Multiple HA deployment modes• Configuration and session synchronization amongmultiple devicesUser and Device Identity• Local user database• Remote user authentication: TACACS+, LDAP,Radius, Active• Single-sign-on: Windows AD• 2-factor authentication: 3rd party support,integrated token server with physical and SMS• User and device-based policies• User group synchronization based on AD andLDAP• Support for 802.1X, SSO Proxy• WebAuth page customization• Interface based Authentication• Agentless ADSSO (AD Polling)• Use authentication synchronization based onSSO-monitor• Support MAC-based user authenticationAdministration• Management access: HTTP/HTTPS, SSH, telnet,console• Central Management: Hillstone Security Manager(HSM), web service APIs• System Integration: SNMP, syslog, alliancepartnerships• Rapid deployment: USB auto-install, local andremote script execution• Dynamic real-time dashboard status and drill-inmonitoring widgets• Language support: EnglishLogs & Reporting• Logging facilities: local memory and storage (ifavailable), multiple syslog servers and multipleHillstone Security Audit (HSA) platforms• Encrypted logging and log integrity with HSAscheduled batch log uploading• Reliable logging using TCP option (RFC 3195)• Detailed traffic logs: forwarded, violated sessions,local traffic, invalid packets, URL etc.• Comprehensive event logs: system and adminis-trative activity audits, routing & networking, VPN,user authentications, WiFi related events• IP and service port name resolution option• Brief traffic log format option• Three predefined reports: Security, Flow andnetwork reports• User defined reporting• Reports can be exported in PDF, Word and HTMLvia Email and FTPStatistics and Monitoring• Application, URL, threat events statistic andmonitoring• Real-time traffic statistic and analytics• System information such as concurrent session,CPU, Memory and temperature• iQOS traffic statistic and monitoring, link statusmonitoring• Support traffic information collection andforwarding via Netflow (v9.0)CloudView• Cloud-based security monitoring• 7/24 access from web or mobile application• Device status, traffic and Threat monitoring• Cloud-based log retention and reportingIoT Security• Identify IoT devices such as IP Cameras andNetwork Video Recorders• Support query of monitoring results based onfiltering conditions, including device type, IPaddress, status, etc.• Support customized whitelistsExpasion Module Option IOC-4GE-B-M, IOC-8GE-M, IOC-8SFP-M IOC-4GE-B-M, IOC-8GE-M, IOC-8SFP-M, IOC-4SFP+, IOC-8SFP+, IOC-2SFP+-Lite Twin-mode HAN/AYesMaximum Power Consumption 1 x 150W Redundancy 1 + 1 2 x 450W Redundancy 1 + 1Power SupplyAC 100-240V 50/60Hz AC 100-240V 50/60Hz DC -40 ~ -60VDimension (W×D×H, mm)1U 17.2 x 14.4x 1.7 in (436 x 366 x 44 mm)2U 17.3 x 20.9 x 3.5 in (440 x530 x 88 mm)Weight 12.3lb (5.6kg)27.1 lb (11.8kg)Temperature 32-104 F (0-40°C)32-104 F (0-40°C)Relative Humidity10-95% (no dew)10-95% (no dew)Compliance and CertificateCE, CB, FCC, UL/cUL, ROHS, IEC/EN61000-4-5 Power Surge Protection, ISO 9001:2015, ISO 14001:2015, CVE Compatibility, IPv6 Ready, ICSA FirewallsNames 8SFP Extension Module 4GE Bypass Extension 2SFP+ Extension Module 4SFP+ Extension ModuleI/O Ports 8 x SFP , SFP module not included2 x SFP+, SFP+ module not included 4 x SFP+, SFP+ module not included Dimension ½U (Occupies 1 generic slots)½ U (Occupies 1 generic slot) 1 U (Occupies 2 generic slots)Weight2.0 lb (0.9kg)0.7 lb (0.3kg)1.5 lb (0.7kg)Module OptionsNOTES:(1) FW throughput data is obtained under single-stack UDP traffic with 1518-byte packet size;(2) IPSec throughput data is obtained under Preshare Key AES256+SHA-1 configuration and 1400-byte packet size packet; (3) AV throughput data is obtained under HTTP traffic with file attachment;(4) IPS throughput data is obtained under bi-direction HTTP traffic detection with all IPS rules being turned on; (5) IMIX throughput data is obtained under UDP traffic mix (64 byte : 512 byte : 1518 byte =5:7:1);(6) NGFW throughput data is obtained under 64 Kbytes HTTP traffic with application control and IPS enabled;(7) Threat protection throughput data is obtained under 64 Kbytes HTTP traffic with application control, IPS, AV and URL filtering enabled; (8) New Sessions/s is obtained under TCP traffic.Unless specified otherwise, all performance, capacity and functionality are based on StoneOS5.5R7. Results may vary based on StoneOS ® version and deployment.IOC-8GE-MIOC-8SFP-MIOC-4GE-B-MIOC-2SFP+-LiteIOC-8SFP+IOC-4SFP+。
瑞典开发出绘制免疫图谱新方法
佚名
【期刊名称】《环境科学与管理》
【年(卷),期】2024(49)4
【摘要】瑞典卡罗林斯卡医学院、皇家理工学院、国家生命科学实验室(SciLifeLab)联合开发了一种识别免疫细胞受体并定位其组织位置的新方法,为识别和预测免疫细胞在病理过程中的作用机制,开发新免疫治疗方法提供了新工具和思路,研究成果发表在《科学》期刊。
【总页数】1页(P60-60)
【正文语种】中文
【中图分类】R73
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2.绘制平面四杆机构连杆图谱的新方法
3.绘制挖掘机作业性能图谱的新方法
4.王菁教授团队研发出活体绘制脑功能连接组的新方法
5.瑞典开发出不用注射胰岛素治疗糖尿病的新方法
因版权原因，仅展示原文概要，查看原文内容请购买。
李春燕，魏福晓，王瑜，等. 茶叶酵素无机陶瓷膜过滤工艺优化[J]. 食品工业科技，2024，45（4）：180−186. doi: 10.13386/j.issn1002-0306.2023040166LI Chunyan, WEI Fuxiao, WANG Yu, et al. Optimization of Inorganic Ceramic Membrane Filtration Process for Tea Enzymes[J].Science and Technology of Food Industry, 2024, 45(4): 180−186. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023040166· 工艺技术 ·茶叶酵素无机陶瓷膜过滤工艺优化李春燕，魏福晓，王 瑜，张朝举，徐甜甜，王道平*（贵州省天然产物研究中心，贵州医科大学，省部共建药用植物功效与利用国家重点实验室，贵州贵阳 550014）摘 要：为了提高茶叶酵素的澄清度，同时保证茶叶酵素在澄清过程中功能成分得到最大的保留，本试验以夏秋茶发酵所得茶叶酵素为原料，采用单因素实验和响应面试验考察无机陶瓷膜孔径、过膜功率、过膜压力、过膜温度对过膜后酵素液功能成分含量、膜通量、透光率、可溶性固形物含量的影响，旨在优选出最佳的茶叶酵素陶瓷膜过滤条件。
结果表明，茶叶酵素陶瓷膜过滤的最佳条件为：膜孔径400 nm 、过膜功率47 Hz 、过膜压力0.28±0.02 MPa ，过膜温度15±2 ℃，在此条件下，茶叶酵素中茶多酚含量保留率为95.28%，茶氨酸含量保留率为82.91%，锌含量保留率为90.48%，硒含量保留率为91.67%，可溶性固形物含量保留率为84.46%，透光率为85.10%±0.12%，透光率与过膜前相比提高了2.5倍，膜通量为123.25±2.68 m 3/（m 2·h ），该条件既能最大程度的保留茶叶酵素中功能成分的含量，又能使茶叶酵素透亮、均一。
ARTICLEReceived1Apr2014|Accepted9Jan2015|Published24Feb2015Observation of long-lived interlayer excitonsin monolayer MoSe2–WSe2heterostructuresPasqual Rivera1,John R.Schaibley1,Aaron M.Jones1,Jason S.Ross2,Sanfeng Wu1,Grant Aivazian1,Philip Klement1,Kyle Seyler1,Genevieve Clark2,Nirmal J.Ghimire3,4,Jiaqiang Yan4,5,D.G.Mandrus3,4,5, Wang Yao6&Xiaodong Xu1,2Van der Waals bound heterostructures constructed with two-dimensional materials,such asgraphene,boron nitride and transition metal dichalcogenides,have sparked wide interest indevice physics and technologies at the two-dimensional limit.One highly coveted hetero-structure is that of differing monolayer transition metal dichalcogenides with type-II bandalignment,with bound electrons and holes localized in individual monolayers,that is,interlayer excitons.Here,we report the observation of interlayer excitons in monolayerMoSe2–WSe2heterostructures by photoluminescence and photoluminescence excitationspectroscopy.Wefind that their energy and luminescence intensity are highly tunable by anapplied vertical gate voltage.Moreover,we measure an interlayer exciton lifetime of B1.8ns,an order of magnitude longer than intralayer excitons in monolayers.Our work demonstratesoptical pumping of interlayer electric polarization,which may provoke further explorationof interlayer exciton condensation,as well as new applications in two-dimensional lasers,light-emitting diodes and photovoltaic devices.1Department of Physics,University of Washington,Seattle,Washington98195,USA.2Department of Materials Science and Engineering,University of Washington,Seattle,Washington98195,USA.3Department of Physics and Astronomy,University of T ennessee,Knoxville,T ennessee37996,USA.4Materials Science and T echnology Division,Oak Ridge National Laboratory,Oak Ridge,T ennessee37831,USA.5Department of Materials Science and Engineering,University of T ennessee,Knoxville,T ennessee37996,USA.6Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong,Hong Kong,China.Correspondence and requests for materials should be addressed to P.R.(email:pasqual@)or to X.X. (email:xuxd@).T he recently developed ability to vertically assemble different two-dimensional(2D)materials heralds a newrealm of device physics based on van der Waals heterostructures(HSs)1.The most successful example to date is the vertical integration of graphene on boron nitride.Such novel HSs not only markedly enhance graphene’s electronic properties2, but also give rise to superlattice structures demonstrating exotic physical phenomena3–5.A fascinating counterpart to gapless graphene is a class of monolayer direct bandgap semiconductors, namely transition metal dichalcogenides(TMDs)6–8.Due to the large binding energy in these2D semiconductors,excitons dominate the optical response,exhibiting strong light–matter interactions that are electrically tunable9,10.The discovery of excitonic valley physics11–15and strongly coupled spin and pseudospin physics16,17in2D TMDs opens up new possibilities for device concepts not possible in other material systems. Monolayer TMDs have the chemical formula MX2where the M is tungsten(W)or molybdenum(Mo),and the X is sulfur(S) or selenium(Se).Although these TMDs share the same crystalline structure,their physical properties,such as bandgap,exciton resonance and spin–orbit coupling strength,can vary signifi-cantly.Therefore,an intriguing possibility is to stack different TMD monolayers on top of one another to form2D HSs.First-principle calculations show that heterojunctions formed between monolayer tungsten and molybdenum dichalcogenides have type-II band alignment18–20.Recently,this has been confirmed by X-ray photoelectron spectroscopy and scanning tunnelling spectroscopy21.Since the Coulomb binding energy in2D TMDs is much stronger than in conventional semiconductors, it is possible to realize interlayer excitonic states in van der Waals bound heterobilayers,that is,bound electrons and holes that are localized in different layers.Such interlayer excitons have been intensely pursued in bilayer graphene for possible exciton condensation22,but direct optical observation demonstrating the existence of such excitons is challenging owing to the lack of a sizable bandgap in graphene.Monolayer TMDs with bandgaps in the visible range provide the opportunity to optically pump interlayer excitons,which can be directly observed through photoluminescence(PL)measurements.In this report,we present direct observation of interlayer excitons in vertically stacked monolayer MoSe2–WSe2HSs.We show that interlayer exciton PL is enhanced under optical excitation resonant with the intralayer excitons in isolated monolayers,consistent with the interlayer charge transfer resulting from the underlying type-II band structure.We demonstrate the tuning of the interlayer exciton energy by applying a vertical gate voltage,which is consistent with the permanent out-of-plane electric dipole nature of interlayer excitons.Moreover,wefind a blue shift in PL energy at increasing excitation power,a hallmark of repulsive dipole–dipole interac-tions between spatially indirect excitons.Finally,time-resolved PL measurements yield a lifetime of1.8ns,which is at least an order of magnitude longer than that of intralayer excitons.Our work shows that monolayer semiconducting HSs are a promising platform for exploring new optoelectronic phenomena.ResultsMoSe2–WSe2HS photoluminescence.HSs are prepared by standard polymethyl methacrylate(PMMA)transfer techniques using mechanically exfoliated monolayers of WSe2and MoSe2(see Methods).Since there is no effort made to match the crystal lattices of the two monolayers,the obtained HSs are considered incom-mensurate.An idealized depiction of the vertical MoSe2–WSe2HS is shown in Fig.1a.We have fabricated six devices that all show similar results as those reported below.The data presented here are from two independent MoSe2–WSe2HSs,labelled device1and device2.Figure1b shows an optical micrograph of device1,which has individual monolayers,as well as a large area of vertically stacked HS.This device architecture allows for the comparison of the excitonic spectrum of individual monolayers with that of the HS region,allowing for a controlled identification of spectral changes resulting from interlayer coupling.We characterize the MoSe2–WSe2monolayers and HS using PL measurements.Inspection of the PL from the HS at room temperature reveals three dominant spectral features(Fig.1c). The emission at1.65and1.57eV corresponds to the excitonic states from monolayer WSe2and MoSe2(refs10,15),respectively. PL from the HS region,outlined by the dashed white line in Fig.1a,reveals a distinct spectral feature at1.35eV(X I).Two-dimensional mapping of the spectrally integrated PL from X I shows that it is isolated entirely to the HS region(inset,Fig.1c), with highly uniform peak intensity and spectral position (Supplementary Materials1).Low-temperature characterization of the HS is performed with 1.88eV laser excitation at20K.PL from individual monolayer WSe2(top),MoSe2(bottom)and the HS area(middle)are shown with the same scale in Fig.1d.At low temperature,the intralayer neutral(X M o)and charged(X MÀ)excitons are resolved10,15,where M labels either W or parison of the three spectra shows that both intralayer X M o and X MÀexist in the HS with emission at the same energy as from isolated monolayers,demonstrating the preservation of intralayer excitons in the HS region.PL from X I becomes more pronounced and is comparable to the intralayer excitons at low temperature.We note that the X I energy position has variation across the pool of HS samples we have studied (Supplementary Fig.1),which we attribute to differences in the interlayer separation,possibly due to imperfect transfer and a different twisting angle between monolayers.We further perform PL excitation(PLE)spectroscopy to investigate the correlation between X I and intralayer excitons.A narrow bandwidth(o50kHz)frequency tunable laser is swept across the energy resonances of intralayer excitons(from1.6to 1.75eV)while monitoring X I PL response.Figure2a shows an intensity plot of X I emission as a function of photoexcitation energy from device2.We clearly observe the enhancement of X I emission when the excitation energy is resonant with intralayer exciton states(Fig.2b).Now we discuss the origin of X I.Since X I has never been observed in our exfoliated monolayer and bilayer samples,if its origin were related to defects,they must be introduced by the fabrication process.This would result in sample-dependent X I properties with non-uniform spatial dependence.However,our data show that key physical properties of X I,such as the resonance energy and intensity,are spatially uniform and isolated to the HS region(inset of Fig.1c and Supplementary Fig.2).In addition,X I has not been observed in WSe2–WSe2homo-structures constructed from exfoliated or physical vapor deposi-tion(PVD)grown monolayers(Supplementary Fig.3).All these facts suggest that X I is not a defect-related exciton.Instead,the experimental results support the observation of an interlayer exciton.Due to the type-II band alignment of the MoSe2–WSe2HS18–20,as shown in Fig.2c,photoexcited electrons and holes will relax(dashed lines)to the conduction band edge of MoSe2and the valence band edge of WSe2,respectively.The Coulomb attraction between electrons in the MoSe2and holes in the WSe2gives rise to an interlayer exciton,X I,analogous to spatially indirect excitons in coupled quantum wells.The interlayer coupling yields the lowest energy bright exciton in the HS,which is consistent with the temperature dependence of X I PL,that is,it increases as temperature decreases (Supplementary Fig.4).From the intralayer and interlayer exciton spectral positions,we can infer the band offsets between the WSe 2and MoSe 2monolayers (Fig.2c).The energy difference between X W and X I at room temperature is 310meV.Considering the smaller binding energy of interlayer than intralayer excitons,this sets a lower bound on the conduction band offset.The energy difference between X M and X I then provides a lower bound on the valence band offset of 230meV.This value is consistent with the valence band offset of 228meV found in MoS 2–WSe 2HSs by micro X-ray photoelectron spectroscopy and scanning tunnelling spectro-scopy measurements 21.This experimental evidence strongly corroborates X I as an interlayer exciton.The observation of bright interlayer excitons in monolayer semiconducting HSs is of central importance,and the remainder of this paper will focus on their physical properties resulting from their spatially indirect nature and the underlying type-II band alignment.WSe 2HSMoSe 2W M SeIn te n s i t y (a .u .)1.31.51.7Energy (eV)MoSe 2HeterostructureWSe 2W0WX X X X −0MoMo−e hehe h1.3 1.41.51.6 1.7I n t e n s i t y (a .u .)Energy (eV)5μm 0123×104Y (μm )246X (μm)0246Figure 1|Intralayer and interlayer excitons of a monolayer MoSe 2–WSe 2vertical heterostructure.(a )Cartoon depiction of a MoSe 2–WSe 2heterostructure (HS).(b )Microscope image of a MoSe 2–WSe 2HS (device 1)with a white dashed line outlining the HS region.(c )Room-temperature photoluminescence of the heterostructure under 20m W laser excitation at 2.33eV.Inset:spatial map of integrated PL intensity from the low-energy peak (1.273–1.400eV),which is only appreciable in the heterostructure area,outlined by the dashed black line.(d )Photoluminescence of individual monolayers and the HS at 20K under 20m W excitation at 1.88eV (plotted on the samescale).Energy (eV)WSe MoSe PL energy (eV)E x c i t a t i o n e n e r g y (e V )1.28 1.3 1.32 1.34 1.36 1.381.61.651.71.754,0006,0008,00010,000IntensityFigure 2|Photoluminescence excitation spectroscopy of the interlayer exciton at 20K.(a )PLE intensity plot of the heterostructure region with an excitation power of 30m W and 5s charge-coupled device CCD integration time.(b )Spectrally integrated PLE response (red dots)overlaid on PL (black line)with 100m W excitation at 1.88eV.(c )Type-II semiconductor band alignment diagram for the 2D MoSe 2–WSe 2heterojunction.interlayer exciton .Applying vertical energy of Figure 3a contact stacked insu-Electrostatic contact shows the 100to about analogue of reversed,varied expected for from reduces device 2,conduction 3b,c.of the in the on top band-offset at X I PL energy of basis of would should have X I PL This effect,intensity.further Power dependence and lifetime of interlayer exciton PL .The interlayer exciton PLE spectrum as a function of laser power with excitation energy in resonance with X W o reveals several properties of the X I .Inspection of the normalized PLE intensity (Fig.4a)shows the evolution of a doublet in the interlayer excitonspectrum,highlighted by the red and Both peaks of the doublet display a consistent increased laser intensity,shown by the dashed which are included as a guide to the eye.intensity of X I also exhibits a strong saturation laser power,as shown in Fig.4b (absolute Supplementary Fig.6).The sublinear power excitation powers above 0.5m W is distinctly the intralayer excitons in isolated monolayers,saturation power threshold of about Fig.7).The low power saturation of X I PL lifetime than that of intralayer excitons.the intralayer exciton is substantially reduced interlayer charge hopping 23,which is quenching of intralayer exciton PL (Fig.Fig.8).Moreover,the lifetime of the interlayer because it is the lowest energy configuration indirect nature leads to a reduced optical long lifetime is confirmed by time-resolved Fig.4c.A fit to a single exponential decay exciton lifetime of 1.8±0.3ns.This timescale the intralayer exciton lifetime,which is ps 24–27.By modelling the saturation behaviour three-level diagram,the calculated saturation interlayer exciton is about 180times (Supplementary Fig.7;Supplementary with our observation of low saturation intensity DiscussionWe attribute the observed doublet feature splitting of the monolayer MoSe 2conduction assignment is mainly based on the fact difference between the doublet is B 25with MoSe 2conduction band splitting predicted calculations 28.This explanation is also supported by the evolution of the relative strength of the two peaks with increasing excitation power,as shown in Fig.4a (similar results in device 1with 1.88eV excitation shown in Supplementary Fig.9).At low power,the lowest energy configuration of interlayer excitons,with the electron in the lower spin-split band of MoSe 2,is populated first.Due to phase space filling effects,the interlayer excitonSiO 2n + Si2MoSe 2e –h +e –h +P Ee –h +V g < 0WSe 2MoSe 2WSe 2MoSe 2h ωV g = 0Photon energy (eV)1.321.361.41.444080e –h +h +PL intensity (a.u.) -hω’-the interlayer exciton and band alignment.(a )Device 2geometry.The interlayer exciton has a out-of-plane electric polarization.(b )Electrostatic control of the band alignment and the interlayer exciton photoluminescence as a function of applied gate voltage under 70m W excitation at 1.744eV,1s integrationconfiguration with the electron in the higher energy spin-split band starts to be filled at higher laser power.Consequently,the higher energy peak of the doublet becomes more prominent at higher excitation powers.The observed blue shift of X I as the excitation power increases,indicated by the dashed arrows in Fig.4a,is a signature of the repulsive interaction between the dipole-aligned interlayer excitons (cf.Fig.3a).This is a hallmark of spatially indirect excitons in gallium arsenide (GaAs)coupled quantum wells,which have been intensely studied for exciton Bose-Einstein condensation (BEC)phenomena 29.The observation of spatially indirect interlayer excitons in a type-II semiconducting 2D HS provides an intriguing platform to explore exciton BEC,where the observed extended lifetimes and repulsive interactions are two key ingredients towards the realization of this exotic state of matter.Moreover,the extraordinarily high binding energy for excitons in this truly 2D system may provide for degenerate exciton gases at elevated temperatures compared with other material systems 30.The long-lived interlayer exciton may also lead to new optoelectronic applications,such as photovoltaics 31–34and 2D HS nanolasers.MethodsDevice fabrication .Monolayers of MoSe 2are mechanically exfoliated onto 300nm SiO 2on heavily doped Si wafers and monolayers of WSe 2onto a layer of PMMA atop polyvinyl alcohol on Si.Both monolayers are identified with an opticalmicroscope and confirmed by their PL spectra.Polyvinyl alcohol is dissolved in H 2O and the PMMA layer is then placed on a transfer loop or thin layer of poly-dimethylsiloxane (PDMS).The top monolayer is then placed in contact with the bottom monolayer with the aid of an optical microscope and micromanipulators.The substrate is then heated to cause the PMMA layer to release from the transfer media.The PMMA is subsequently dissolved in acetone for B 30min and then rinsed with isopropyl alcohol.Low-temperature PL measurements .Low-temperature measurements are con-ducted in a temperature-controlled Janis cold finger cryostat (sample in vacuum)with a diffraction-limited excitation beam diameter of B 1m m.PL is spectrally filtered through a 0.5-m monochromator (Andor–Shamrock)and detected on a charge-coupled device (Andor—Newton).Spatial PL mapping is performed using a Mad City Labs Nano-T555nanopositioning system.For PLE measurements,a continuous wave Ti:sapphire laser (MSquared—SolsTiS)is used for excitation and filtered 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chalcogenides.Proc.Natl A111,6198–6202 (2014).AcknowledgementsThis work is mainly supported by the US DoE,BES,Materials Sciences and Engineering Division(DE-SC0008145).N.J.G.,J.Y.and D.G.M.are supported by US DoE,BES, Materials Sciences and Engineering Division.W.Y.is supported by the Research Grant Council of Hong Kong(HKU17305914P,HKU9/CRF/13G),and the Croucher Foun-dation under the Croucher Innovation Award.X.X.thanks the support of the Cottrell Scholar Award.P.R.thanks the UW GO-MAP program for their support.A.M.J.is partially supported by the NSF(DGE-0718124).J.S.R.is partially supported by the NSF (DGE-1256082).S.W.and G.C.are partially supported by the State of Washington through the UW Clean Energy Institute.Device fabrication was performed at the Washington Nanofabrication Facility and NSF-funded Nanotech User Facility. Author contributionsX.X.and P.R.conceived the experiments.P.R.and P.K.fabricated the devices,assisted by J.S.R.P.R.performed the measurements,assisted by J.R.S.,A.M.J.,J.S.R.,S.W.and G.A. P.R.and X.X.performed data analysis,with input from W.Y.N.J.G.,J.Y.and D.G.M. synthesized and characterized the bulk WSe2crystals.X.X.,P.R.,J.R.S.and W.Y.wrote the paper.All authors discussed the results.Additional informationSupplementary Information accompanies this paper at / naturecommunicationsCompetingfinancial interests:The authors declare no competingfinancial interests. Reprints and permission information is available online at / reprintsandpermissions/How to cite this article:Rivera,P.et al.Observation of long-lived interlayer excitons in monolayer MoSe2–mun.6:6242doi:10.1038/ncomms7242(2015).。
