Multiphonon absorption in InP

IR absorption measurements have been made using a high resolution Fourier-transform spectrometer on crystals of InP in the region of (400–4000)cm^-1 at temperature between 11–300k. Very weak, new absorption bands, their absorption coefficients are of ∼10^-1cm^-1, were observed at 996cm^-1, 965cm^-1, 932cm^-1, 838cm^-1, 776cm^-1, 742cm^-1, 718cm^-1, 590cm^-1, 558cm^-1 and 538cm^-1. The frequencies and temperature dependence of these weak bands indicate that they arise from three-phonon processes and appropriate assignments are given. We observed using IR absorption technique for the first time the boron contamination in LEC(B₂O₃)-CZ InP crystal. The content of boron contamination has been proved to be of ∼10¹⁶cm^-3.     

InP的多声子红外吸收

利用高分辨的傅里叶光谱仪,在400—4000cm^-1和11—300K范围内,观察到一些其吸收系数为10^-1cm^-1的新弱吸收峰,频率位置为996,965,932,838,806,776,742,718,590,558,538cm^-1。从这些弱吸收峰的频率位置和温度依赖关系,可以认为它们是由于三声子的晶格吸收过程所引起的。对此,我们做了适当的指认。此外,我们首次利用红外吸收法证实,LEC(B₂O₃)-CZInP单晶存在B玷污,其玷污量大约是10¹⁶cm^-3。 关键词：     

CF3CDCl2分子红外多光子光热吸收谱

本文报道用铂丝光热吸收池作为探测器得到了CF₃CDCI₂的红外多光子吸收谱。并发现在线性吸收谱中944cm^-1处的吸收峰在多光子吸收谱中分裂为947cm^-1和927cm^-1两个吸收峰。这一现象与科里奥利力和非谐性引起的简正振动的耦合作用有关。这样,在用CF₃CDCI₂/CF₃CHCI₂体系分离氘同位素时,可以根据这一新结果选择更合适的激发波长。实验还发现在线性吸收谱中986cm^-1处的吸收峰在多光子吸收谱中出现约6cm^-2的红移。这种红移现象起源于分子振动能级的非谐性。 关键词：     

氮氢共掺杂金刚石中氢的典型红外特征峰的表征

所有天然Ia型金刚石红外光谱中都存在3107 cm-1特征峰,而在金属触媒直接合成的金刚石红外光谱中没有检测出3107 cm-1特征峰.本文在6.3 GPa,1500?C条件下,通过Fe70Ni30触媒中添加P3N5直接合成出具有3107 cm-1特征峰的氮氢共掺杂的金刚石.红外光谱分析表明,合成的金刚石中氢有两种存在形式:一种对应着乙烯基团C=CH2中C—H键的伸缩振动(3107 cm-1)和弯曲振动(1450 cm-1)的吸收峰,另一种对应着sp3杂化C—H键的对称伸缩振动(2850 cm-1)和反对称伸缩振动(2920 cm-1)的吸收峰.通过分析发现,3107 cm-1吸收峰与金刚石中聚集态的氮原子有关,当金刚石中没有聚集态的氮元素时,即使氮含量高也不会出现3107 cm-1峰;并且2850和2920 cm-1附近的吸收峰比3107 cm-1附近的吸收峰更为普遍存在.这说明sp3杂化C—H键比乙烯基团的C—H键更广泛存在于金刚石中,从两者的峰值看,天然金刚石中的氢杂质主要以乙烯基团C=CH2存在.3107 cm-1吸收峰与聚集态的氮原子的这种存在关系为天然金刚石形成机制的研究提供了一种新思路,同时较低的合成条件也可能为氢与其他元素共掺杂合成具有n型半导体特性的金刚石提供一个较理想的合成环境.     

Quantum cascade laser-based carbon monoxide detection on a second time scale from human breath

We present three different detection schemes for measuring carbon monoxide (CO) in direct absorption using a thermoelectrically cooled, distributed-feedback pulsed quantum cascade (qc) laser operating between 2176 and 2183 cm^-1. The laser emission has overlap with the strong R(8)1 ro-vibrational transition in CO at 2176.2835 cm^-1. Firstly, by utilizing the frequency chirp of the qc-laser with long laser pulses, a minimal detectable absorption of 1.2×10^-5 cm^-1 is achieved at an acquisition rate of 3 Hz. Additionally, with short laser pulses and slow frequency scanning a minimal detectable absorption 8.2×10^-7 cm^-1 is reported, with an acquisition time of 60 s. Finally, a novel amplitude modulation technique is developed to facilitate real-time measurement of CO in exhaled air. The application of this detector to detection of CO in a single breath as a potential non-invasive diagnostic tool is shown. PACS 07.07.Df; 42.62.Be     

多光程吸收的频率调制光谱

采用可连续调谐的半导体二极管激光器作探测光源,将多光程吸收光谱技术、频率调制光谱技术和相敏检波技术相结合,建立了一套具有高检测灵敏度和分辨率的测量气态分子光谱和进行微量分析的研究装置并利用该装置研究了动态分压强为40Pa和120Pa时,H₂O分子在7462cm^-1和7473cm^-1附近的近红外吸收光谱,检测灵敏度远高于传统吸收光谱技术,为气态分子的光谱研究和微量分析提供了一种高灵敏度的光谱检测方法.     

A novel technique for measuring absorption coefficients at 632.8 nm

A novel experimental technique is reported for the determination of the absorption coefficients of modern optical materials at the 632.8 nm with the help of a high power He-Ne laser. Sensitive dependence of the laser output on the intra-cavity optical losses of the laser has been utilized. Absorption in these materials are very small, and their measurements are beyond the capabilities of the existing instrumentation. Hence the technique described in this paper would excel. The absorption coefficients of boro-silicate crown glass and fused silica have been determined, and are found to be 0.008 and 0.001 cm^-1, respectively. This technique is capable of measuring absorptions ～ 10^-4 cm^-1, and can be improvised to measure absorptions ～ 10^-5 cm^-1.     

Absorption coefficients for hydrogen—III. calculated pressure-induced H2-H vibrational absorption in the fundamental region

The coefficient for absorption during H₂-H collisions was calculated for temperatures from 2000 to 7000 K and wave numbers between 100 and 40 000 cm^-1 for LTE. Because only transitions with Δν = 1 were considered, the absorption was near the fundamental at 4161 cm^-1 in the infrared. The model included mechanical anharmonicity, vibration-rotation interaction, excited vibrational states, and transverse components of the dipole moment. At 5500 cm^-1, 3750° K, and 1 atm pressure, inclusion of H₂-H vibrational absorption increased the absorption of pure hydrogen gas 48 per cent. An approximate formula for the H²-H absorption coefficient is given for rapid calculation.     

3Cu(IO3)2·2H2O晶体的电子结构研究

本文测定了3Cu(IO₃)₂·2H₂O球晶的电子吸收光谱,吸收峰位于9140cm^-1和15250cm^-1。首次观察到了高达6110cm^-1的低对称晶场分裂。吸收曲线经Gauss分解可得到八个Gauss型吸收峰,分别位于8590,10690,10870,12190,13500,14510,15330和16500cm^-1。测量其EPR谱可得g=2.141±0 关键词：     

中子辐照含氢FZ-Si的红外吸收研究

对于中子辐照的n-FZSi(H₂),利用红外吸收光谱研究了由于辐照所产生的各种与氢有关的缺陷态。在未辐照的样品和辐照的样品中分别发现了未曾报道的1992cm^{-1和1857cm-1吸收峰。对于在n-FZSi(H₂)所引起的本征吸收峰和辐照损伤吸收峰,进行了讨论和指派。2150cm-1吸收峰则被认为是由于氢施主所引起的。 关键词：}     

Ag离子注入非晶SiO2的光学吸收、拉曼谱和透射电镜研究

能量为200keV的Ag离子，以1×10¹⁶，5×10¹⁶，1×10¹⁷ cm^-2的剂量分别注入到非晶SiO₂玻璃，光学吸收谱显示：注入剂量为1×10¹⁶ cm^-2的样品的光吸收谱为洛伦兹曲线，与Mie理论模拟的曲线形状一致；注入剂量较大的5×10¹⁶，1×10¹⁷ cm^-2的谱线共振吸收增强，峰位红移并出现伴峰. 透射电镜观察分析表明，注入剂量不同的样品中形成的纳米颗粒的大小、形状、分布都不同，注入剂量较大的还会产生明显的表面溅射效应，这些因素都会影响共振吸收的峰形、峰位和峰强. 当注入剂量达到1×10¹⁷ cm^-2时，Ag纳米颗粒内部可能还形成了杂质团簇. 关键词： 离子注入 纳米颗粒 共振吸收 红移     

Optical study of RE 1 + x Ba 2 - x Cu 3 O 6 (RE = Nd, Sm) aaand YBa 2 Cu 3 O 6 in the mid infrared range

Infrared reflectance, and transmission measurements as well as Raman scattering have been used to study the RE_1+xBa_2-xCu₃O₆ (RE = Nd, Sm) and YBa₂Cu₃O₆ absorption bands in the 1100-1500 cm^-1 infrared range as a function of temperature and beam polarization. In addition to two-phonon absorption between 1100 and 1170 cm^-1, we observe excitations around 1400 cm^-1, occurring in oxygen rich enclosures within the samples, and assign them to an excitation involving two-phonons plus the 270 cm^-1 local mode related to Cu-O broken chains. Thus, the previously reported possible magnetic origin of the 1436 cm^-1 sharp absorption band in YBa₂Cu₃O₆ is contested. Received 14 February 2001 and Received in final form 12 April 2001     

Infrared spectra of paraelectric and ferroelectric CsH2PO4

ir spectra are reported for polycrystalline CsH₂PO₄ above and below the transformation temperature, 153 K. Three absorption bands at 1760 cm^-1 2350 cm^-1 and 2800 cm^-1 are assigned to -OHO- vibrations. Whilst the 2350 cm^-1 band remains essentially unaltered, the 1760 cm^-1 band splits into multiplets and the 2800 cm^-1 band shifts to lower frequency on cooling below 153 K. A broad band centred at 3240 cm^-1 is found to exist in the ferroelectric phase and is associated with the -OHO- mode involving the H(2) proton ordered below the transition.     

Three-photon absorption and subsequent excited-state absorption in CdS

The nonlinear absorption of single picosecond light pulses (λ = 1.06 μm) in CdS is investigated at very high light intensities. Three-photon absorption and subsequent excited-state absorption of the generated electrons and holes explain the rapid decrease of transmission with increasing intensity. A three-photon absorption cross-section of σ⁽³⁾ = (2±0.5) × 10^-80 cm⁶ s² and an average excited state absorption cross-section of σ_ex = (7 ± 3) × 10^-18 cm² was determined.     

The rotationally-resolved absorption spectrum of formaldehyde from 6547 to 6804 cm

The room temperature absorption spectrum of formaldehyde, H₂CO, from 6547 to 6804 cm⁻¹ (1527-1470 nm) is reported with a spectral resolution of 0.001 cm⁻¹. The spectrum was measured using cavity-enhanced absorption spectroscopy (CEAS) and absorption cross-sections were calculated after calibrating the system using known absorption lines of H₂O and CO₂. Several vibrational combination bands occur in this region and give rise to a congested spectrum with over 8000 lines observed. Pressure broadening coefficients in N₂, O₂, and H₂CO are reported for an absorption line at 6780.871 cm⁻¹, and in N₂ for an absorption line at 6684.053 cm⁻¹.     

Photo-acoustic and photo-refractive detection of small absorptions in liquids

The sensitivities of pulsed photo-acoustic and photo-refractive (e.g., thermal lensing) techniques for the measurement of small absorptions in liquids have been evaluated both theoretically and experimentally. Electrostriction limits the sensitivity of both techniques, this limitation is less severe for the photo-refractive technique. The minimum absorption constants observed experimentally, for a 200-μm laser spot size in liquid N₂, are 4 × 10^-5 cm^-1 for the photo-acoustic measurement and 6 × 10^-7 cm^-1 for the photo-refractive measurement. The calculated electrostrictive limits are 2 × 10^-5 cm^-1 and 7 × 10^-11 cm^-1, respectively.     

Yb:Y2－2xLa2xO3激光透明陶瓷的光谱性能

对一种低温易烧结的Yb:Y_2-2xLa_2xO₃激光透明陶瓷的光谱性能进行了初步研究，Yb:Y_2-2xLa_2xO₃激光透明陶瓷具有宽的吸收带和大的吸收截面，在最强的吸收峰977nm处吸收截面达4.0×10^-20cm²；其荧光发射寿命为1.1ms，发射截面在1033nm处为1.0×10^-20cm²，在1077nm处为0.7×10^-20cm².Yb:Y_2-2xLa_2xO₃陶瓷的各项光学性能指标接近或达到单晶的指标. 关键词： 氧化镧钇 激光陶瓷 低温烧结 光谱性能     

室温下1.3μm附近CO2的高灵敏度半导体激光吸收光谱

用DFB（分布反馈）半导体激光器结合波长调制吸收光谱技术观测了CO2在1.31μm附近的泛频吸收光谱，并获得的相应的光谱参数（如：谱线位置，谱线强度以及自加宽系数），同时发现了15条弱的新谱线。在665 Pa压力下，本实验可探测的最弱谱线是2.25163′10-27 cm-1/(molecule×cm-2)，相应的吸收是3.88′10-8。     

Optical absorption spectra of synthetic CoCO3 single crystal

New results have been obtained on absorption spectra of synthetic CoCO₃ single crystal in the spectral range from the 11,500 to 34,500 cm^-1. Some vibration frequencies of the (CO₃)^2- ions have deduced from the absorption spectrum and zero-phonon lines have been identified. In the regions 22,900 and 24,500 cm^-1, a shift is observed of absorption frequencies with antiferromagnetic order for temperatures increasing from 4.2 to 20°K.     

砷化镓中微微秒光脉冲的自透射

本文报道了以Brewster角入射的无掺杂半绝缘GaAs的1μm微微秒光脉冲自透射的实验和理论结果。最佳拟合的深能级EL2态的密度为1.2×10¹⁶cm^-3,双光子吸收系数为29cm/GW,自由载流子的吸收截面为2.7×10^-17cm²。 关键词：