We operated a p-type point contact high purity germanium(PPCGe)detector(CDEX-1B,1.008 kg)in the China Jinping Underground Laboratory(CJPL)for 500.3 days to search for neutrinoless double beta(0νββ)decay of ^(76)Ge....We operated a p-type point contact high purity germanium(PPCGe)detector(CDEX-1B,1.008 kg)in the China Jinping Underground Laboratory(CJPL)for 500.3 days to search for neutrinoless double beta(0νββ)decay of ^(76)Ge.A total of 504.3 kg⋅day effective exposure data was accumulated.The anti-coincidence and the multi/single-site event(MSE/SSE)discrimination methods were used to suppress the background in the energy region of interest(ROI,1989–2089 keV for this work)with a factor of 23.A background level of 0.33 counts/(keV⋅kg⋅yr)was realized.The lower limit on the half life of^(76)Ge 0νββdecay was constrained as T_(1/2)^(0ν)>1.0×10^(23)yr(90%C.L.),corresponding to the upper limits on the effective Majorana neutrino mass:<mββ><3.2–7.5 eV.展开更多
The rapid synthesis of structurally complicated electron donors&acceptors still remains a major challenge in organic solar cells(OSC).In this work,we developed a highly efficient strategy to access long-chain olig...The rapid synthesis of structurally complicated electron donors&acceptors still remains a major challenge in organic solar cells(OSC).In this work,we developed a highly efficient strategy to access long-chain oligomeric donor and acceptors for OSC applications.A series of cyclopentadithiophene(CPDT)and benzothiadiazole(BT)-basedπ-conjugated oligomers,i.e.,three oligomeric acceptors(BTDT)n-IC(n=1—3)and one long-chain oligomeric donor(BTDT)4-RD,are facilely synthesized by an atom-and step-economical,and labor-saving direct C—H arylation(DACH)reaction(i.e.,C—H/C—Br cross coupling).Note that(BTDT)4-RD involving five CPDT,four BT and two rhodamine(RD)building blocks is the longest oligomeric donor in the fullerene-free OSC devices ever reported.The dependence of the structure-property-performance correlation of(BTDT)n-IC(n=1—3)and(BTDT)4-RD on theπ-conjugation lengths is thoroughly investigated by opto-electrochemical measurements,bulk heterojunction(BHJ)OSC devices and microscopies.The(BTDT)1-IC:PBDB-T and(BTDT)4-RD:Y6 BHJs achieve power conversion efficiencies of 9.14%and 4.51%,respectively.Our findings demonstrate that DACH reaction is a powerful tool to tune the opto-electronic properties and device performances by regulating the lengths ofπ-conjugated oligomers with varied numbers of repeating units.展开更多
Microstructures of GaN buffer layers grown on Si(111)substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope(AFM)and a high-resolution ...Microstructures of GaN buffer layers grown on Si(111)substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope(AFM)and a high-resolution transmission electron microscope(HBTEM).AFM images show that the islands appear in the GaN buffer layer after annealing at high temperature.Cross-sectional HBTEM micrographs of the buffer region of these samples indicate that there are bunched steps on the surface of the Si substrate and a lot of domains in GaN misorienting each other with small angles.The boundaries of those domains locate near the bunched steps,and the regions of the Him on a terrace between steps have the same crystal orientation.An amorphous-like layer,about 3nm thick,can also be observed between the GaN buffer layer and the Si substrate.展开更多
Sympathetic cooling is a method used to lower the kinetic energy of ions with complicated energy-level structures,via Coulomb interactions with laser-cooled ions in an ion trap.The ion to be sympathetically cooled is ...Sympathetic cooling is a method used to lower the kinetic energy of ions with complicated energy-level structures,via Coulomb interactions with laser-cooled ions in an ion trap.The ion to be sympathetically cooled is sometimes prepared outside of the trap,and it is critical to introduce this ion into the trap by temporarily lowering the potential of one endcap without allowing the coolant ion to escape.We study the time required for a laser-cooled ion to escape from a linear Paul trap when the voltage of one endcap is lowered.The escape time is on the order of a few microseconds,and varies significantly when the low-level voltage changes.A re-cooling time of a maximum of 13 s was measured,which can be reduced to approximately one hundred of milliseconds by decreasing the duration of the low-level voltage.The measurement of these critical values lays the foundation for the smooth injection and cooling of the ion to be sympathetically cooled.展开更多
基金Supported by the National Key Research and Development Program of China(2017YFA0402201,2022YFA1604701,2022YFA1605000)the National Natural Science Foundation of China(12322511,12175112,12005111,11725522)。
文摘We operated a p-type point contact high purity germanium(PPCGe)detector(CDEX-1B,1.008 kg)in the China Jinping Underground Laboratory(CJPL)for 500.3 days to search for neutrinoless double beta(0νββ)decay of ^(76)Ge.A total of 504.3 kg⋅day effective exposure data was accumulated.The anti-coincidence and the multi/single-site event(MSE/SSE)discrimination methods were used to suppress the background in the energy region of interest(ROI,1989–2089 keV for this work)with a factor of 23.A background level of 0.33 counts/(keV⋅kg⋅yr)was realized.The lower limit on the half life of^(76)Ge 0νββdecay was constrained as T_(1/2)^(0ν)>1.0×10^(23)yr(90%C.L.),corresponding to the upper limits on the effective Majorana neutrino mass:<mββ><3.2–7.5 eV.
基金The National Natural Science Foundation of China(No.22169009)Jiangxi Provincial Natural Science Foundation(No.20212ACB204007)Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry(20212BCD42018)are appreciated for financial support。
文摘The rapid synthesis of structurally complicated electron donors&acceptors still remains a major challenge in organic solar cells(OSC).In this work,we developed a highly efficient strategy to access long-chain oligomeric donor and acceptors for OSC applications.A series of cyclopentadithiophene(CPDT)and benzothiadiazole(BT)-basedπ-conjugated oligomers,i.e.,three oligomeric acceptors(BTDT)n-IC(n=1—3)and one long-chain oligomeric donor(BTDT)4-RD,are facilely synthesized by an atom-and step-economical,and labor-saving direct C—H arylation(DACH)reaction(i.e.,C—H/C—Br cross coupling).Note that(BTDT)4-RD involving five CPDT,four BT and two rhodamine(RD)building blocks is the longest oligomeric donor in the fullerene-free OSC devices ever reported.The dependence of the structure-property-performance correlation of(BTDT)n-IC(n=1—3)and(BTDT)4-RD on theπ-conjugation lengths is thoroughly investigated by opto-electrochemical measurements,bulk heterojunction(BHJ)OSC devices and microscopies.The(BTDT)1-IC:PBDB-T and(BTDT)4-RD:Y6 BHJs achieve power conversion efficiencies of 9.14%and 4.51%,respectively.Our findings demonstrate that DACH reaction is a powerful tool to tune the opto-electronic properties and device performances by regulating the lengths ofπ-conjugated oligomers with varied numbers of repeating units.
基金Supported by Project of High Technology Research&Development of China(863-715-011-0030),Project of Fundamental Research of China,the National Natural Science Foundation of China under Grant Nos.69636010 and 69636040,and MOTOROLA(China Inc.)Semiconductor Scholarship.
文摘Microstructures of GaN buffer layers grown on Si(111)substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope(AFM)and a high-resolution transmission electron microscope(HBTEM).AFM images show that the islands appear in the GaN buffer layer after annealing at high temperature.Cross-sectional HBTEM micrographs of the buffer region of these samples indicate that there are bunched steps on the surface of the Si substrate and a lot of domains in GaN misorienting each other with small angles.The boundaries of those domains locate near the bunched steps,and the regions of the Him on a terrace between steps have the same crystal orientation.An amorphous-like layer,about 3nm thick,can also be observed between the GaN buffer layer and the Si substrate.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11934014,11622434 and 11804373)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(Grant No.YZ201552)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB21030100 and XDB21030300)CAS Youth Innovation Promotion Association(Grant Nos.Y201963 and 2018364)the Hubei Province Science Fund for Distinguished Young Scholars(Grant No.2017CFA040)。
文摘Sympathetic cooling is a method used to lower the kinetic energy of ions with complicated energy-level structures,via Coulomb interactions with laser-cooled ions in an ion trap.The ion to be sympathetically cooled is sometimes prepared outside of the trap,and it is critical to introduce this ion into the trap by temporarily lowering the potential of one endcap without allowing the coolant ion to escape.We study the time required for a laser-cooled ion to escape from a linear Paul trap when the voltage of one endcap is lowered.The escape time is on the order of a few microseconds,and varies significantly when the low-level voltage changes.A re-cooling time of a maximum of 13 s was measured,which can be reduced to approximately one hundred of milliseconds by decreasing the duration of the low-level voltage.The measurement of these critical values lays the foundation for the smooth injection and cooling of the ion to be sympathetically cooled.
