为根据斯托克斯频移光信号有效地探测与识别红外频率转换材料,基于铟镓砷（In Ga As）光电二极管构建紧凑型光电探测系统,并对系统进行优化。以镱铒共掺硫氧化钇（Y2O2S：Yb,Er）转换材料为例,给出了980nm激光激发出的下转换斯托克斯频...为根据斯托克斯频移光信号有效地探测与识别红外频率转换材料,基于铟镓砷（In Ga As）光电二极管构建紧凑型光电探测系统,并对系统进行优化。以镱铒共掺硫氧化钇（Y2O2S：Yb,Er）转换材料为例,给出了980nm激光激发出的下转换斯托克斯频移光谱及时间特性,分析了方波调制激光所产生的回波信号的延迟展宽特性,并采用优选调制频率与相位匹配等手段实现基于相敏检波的回波信号解调,提高信噪比。理论分析结合实验测试的结果表明：在20CM的探测距离上,采用频率为60Hz方波调制功率50mw的980nm激光激发Y2O2S：Yb,Er材料,且方波信号相位平移π/8时,回波信号输出直流电压最大,系统探测性能达到最优。展开更多
In our recent work [Phys. Chem. Chem. Phys. 11, 9149 （2009）], a molecular-mechanics force field-based amidc-Ⅰ vibration frequency map （MM-map） for peptides and proteins was constructed. In this work, the temperat...In our recent work [Phys. Chem. Chem. Phys. 11, 9149 （2009）], a molecular-mechanics force field-based amidc-Ⅰ vibration frequency map （MM-map） for peptides and proteins was constructed. In this work, the temperature dependence of the MM-map is examined based on high-temperature molecular dynamics simulations and infrared （IR） experiments. It is shown that the 298-K map works for up to 500-K molecular dynamics trajectories, which reasonably reproduces the 88 ℃ experimental IR results. Linear IR spectra are also simulated for two tripeptides containing natural and unnatural amino acid residues, and the results are in reasonable agreement with experiment. The results suggest the MM-map can be used to obtain the temperature-dependent amide-Ⅰ local mode frequencies and their distributions for peptide oligomers, which is useful in particular for understanding the IR signatures of the thermally unfolded species.展开更多
Ti＋（CO2）2Ar and Ti＋（CO2）n （n=3-7） complexes are produced by laser vaporization in a pulsed supersonic expansion. The ion complexes of interest are each mass-selected in a time- of-flight spectrometer, and stud...Ti＋（CO2）2Ar and Ti＋（CO2）n （n=3-7） complexes are produced by laser vaporization in a pulsed supersonic expansion. The ion complexes of interest are each mass-selected in a time- of-flight spectrometer, and studied with infrared photodissociation spectroscopy. For each complex, a sharp band in the CO stretching frequency region is observed, which confirms the formation of the OTi＋CO（CO2）~_l oxide-carbonyl species. Small OTi＋CO（CO2）~_1 complexes （n_〈5） exhibit CO stretching and antisymmetric CO2 stretching vibrational bands that are blue-shifted from those of free CO and CO2. The experimental observations indicate that the coordination number of CO and CO2 molecules around TiO＋ is five. Evidence is also observed for the presence of another electrostatic bonding Ti＋（CO2）2 structural isomer for the Ti＋（CO2）2Ar complex, which is characterized to have a bent OCO-Ti＋-OCO structure stabilized by argon coordination.展开更多
文摘为根据斯托克斯频移光信号有效地探测与识别红外频率转换材料,基于铟镓砷（In Ga As）光电二极管构建紧凑型光电探测系统,并对系统进行优化。以镱铒共掺硫氧化钇（Y2O2S：Yb,Er）转换材料为例,给出了980nm激光激发出的下转换斯托克斯频移光谱及时间特性,分析了方波调制激光所产生的回波信号的延迟展宽特性,并采用优选调制频率与相位匹配等手段实现基于相敏检波的回波信号解调,提高信噪比。理论分析结合实验测试的结果表明：在20CM的探测距离上,采用频率为60Hz方波调制功率50mw的980nm激光激发Y2O2S：Yb,Er材料,且方波信号相位平移π/8时,回波信号输出直流电压最大,系统探测性能达到最优。
基金This work was supported by the National Natural Science Foundation of China （No.30870591）, the National Basic Research Program of China （No.2007CB815205） and the Chinese Academy of Sciences （Hundred Talent Fund）. Chen Han thanks Dr. Kai-cong Cai for helpful discussions.
文摘In our recent work [Phys. Chem. Chem. Phys. 11, 9149 （2009）], a molecular-mechanics force field-based amidc-Ⅰ vibration frequency map （MM-map） for peptides and proteins was constructed. In this work, the temperature dependence of the MM-map is examined based on high-temperature molecular dynamics simulations and infrared （IR） experiments. It is shown that the 298-K map works for up to 500-K molecular dynamics trajectories, which reasonably reproduces the 88 ℃ experimental IR results. Linear IR spectra are also simulated for two tripeptides containing natural and unnatural amino acid residues, and the results are in reasonable agreement with experiment. The results suggest the MM-map can be used to obtain the temperature-dependent amide-Ⅰ local mode frequencies and their distributions for peptide oligomers, which is useful in particular for understanding the IR signatures of the thermally unfolded species.
文摘Ti＋（CO2）2Ar and Ti＋（CO2）n （n=3-7） complexes are produced by laser vaporization in a pulsed supersonic expansion. The ion complexes of interest are each mass-selected in a time- of-flight spectrometer, and studied with infrared photodissociation spectroscopy. For each complex, a sharp band in the CO stretching frequency region is observed, which confirms the formation of the OTi＋CO（CO2）~_l oxide-carbonyl species. Small OTi＋CO（CO2）~_1 complexes （n_〈5） exhibit CO stretching and antisymmetric CO2 stretching vibrational bands that are blue-shifted from those of free CO and CO2. The experimental observations indicate that the coordination number of CO and CO2 molecules around TiO＋ is five. Evidence is also observed for the presence of another electrostatic bonding Ti＋（CO2）2 structural isomer for the Ti＋（CO2）2Ar complex, which is characterized to have a bent OCO-Ti＋-OCO structure stabilized by argon coordination.
