High resolution FTIR study on NH2Br molecule: amino wagging band

The amino wagging band of NH₂Br molecule has been observed in the region from 800 to 1200 cm⁻¹ with the resolution of 0.006 cm⁻¹ by a Fourier transform spectrometer. The rotational and centrifugal distortion constants have been determined which reproduce the rotational structures of K^′_a<6 for both isotopomers of ⁷⁹Br and ⁸¹Br. The spectral splittings as much as 0.07 cm⁻¹ due to the amino inversion motion have been observed and some discussions on the inversion potential have been made.     

High Resolution FTIR Study on NH(2)Cl Molecule: Inversion and Anharmonicity

The high-resolution FTIR absorption spectra of the NH(2)Cl molecule have been measured in the region 500-3600 cm(-1). The rotational structures of all the fundamental bands and a number of overtone and combination bands have been analyzed. Every rotational line of the observed bands except the NH(2) twisting and stretching fundamental bands splits into two components due to the amino inversion motion. The vibrational anharmonicity and the direction of the transition moments have been studied with the help of B3LYP/6-31++G(**) calculations. The amount of inversion splitting depends on the molecular rotation, and the J,K-dependence of the inversion splitting has been determined. Copyright 2001 Academic Press.     

Amino wagging and torsion vibrations of vinylamine

Far-infrared spectra ov vinylamine and its N-deuterated species were observed in the gas phase at 0.25 cm⁻¹ resolution. Each of the amino wagging and torsion energy levels was found to be split into two by a large amplitude inversion motion of the amino group. Barrier height for the inversion has been estimated to be about 700 (±100) cm⁻¹ and that for the internal rotation 2400 (±200) cm⁻¹.     

The Torsion–Inversion Energy Levels in theS1(n, π*) Electronic State of Acetaldehyde from High-Resolution Jet-Cooled Fluorescence Excitation Spectroscopy

The laser-induced fluorescence excitation spectrum (LIF) of acetaldehyde that results from the emission from theS₁(n, π*) electronic state has been observed under very high resolution with a CW pulse-amplified laser under jet-cooled conditions. The origins of seven bands were determined by rotational analyses with a rigid-rotor Hamiltonian. The origins were fitted to a set of levels that were obtained from a Hamiltonian that employed flexible torsion–wagging large amplitude coordinates. The potential surface derived from the fitting procedure yielded barriers to torsion and inversion of 721.43 and 585.13 cm⁻¹, respectively. Minima in the potential hypersurface at θ = 58.6° and α = 35.7° defined the corresponding equilibrium positions for the torsion and wagging coordinates.     

基于车载被动DOAS系统的化工园区甲醛柱浓度精确反演研究

甲醛（HCHO）是大气中含量最为丰富的羰基化合物,是非甲烷可挥发性有机化合物（NMVOCs）的最重要的中间产物之一,广泛参与大气中的光化学反应,同时也是气溶胶的重要前体物,在大气化学中承担了非常重要的作用。石油化工行业的VOCs类排放是城市大气中HCHO的重要来源,而目前化工园区中的HCHO等NMVOCs类污染物主要通过点式设备获取近地面浓度,缺乏立体监测数据。差分光学吸收光谱（DOAS）技术已成功应用于SO₂和NO₂等污染气体监测,甲醛由于其光学吸收强度相对较弱,反演波段内其他气体交叉干扰强,实际的监测应用相对较少。选取某石化企业,运用被动DOAS方法实现了甲醛柱浓度的精确反演。研究通过建立甲醛吸收截面与其他参与拟合气体吸收截面的二维相关性矩阵,选取甲醛吸收截面同其他气体吸收截面相关性最小的波段,即实现其他气体对甲醛的DOAS反演交叉干扰最小的波段的获取。同时选取外场实际采集的光谱,选择不同起始波段和截止波段做迭代DOAS反演,通过拟合残差来评估甲醛在不同波段的实际反演效果。在截面间交叉干扰小,拟合残差低的波段范围内,选择尽量宽的波段作为最佳的拟合波段,实现甲醛的精确DOAS反演。由甲醛同其他气体吸收截面的二维相关性矩阵结果,甲醛与NO₂,SO₂和O₃和O₄间在大部分波段内相关性均在0.5以下,交叉干扰小;甲醛同BrO在起始波长318～320 nm,截止波长340～346 nm以及起始波长330～334 nm,截止波长354～360 nm两个波段范围内截面间相关性小于0.5,适合作为HCHO的反演波段。通过选择不同起始波段和截止波段做甲醛的迭代DOAS反演,结合拟合截面相关性分析结果综合考虑,最终采用332.4～358.1 nm作为HCHO的反演波段,拟合残差在10-4量级。利用车载被动DOAS系统,通过建立吸收截面间二维相关性矩阵并通过实测光谱的迭代反演,获取了适用于该套系统的HCHO最佳拟合波段,拟合残差降低至10-4量级,在实现甲醛精确反演的基础上,结合系统GPS信息,获取了某化工企业甲醛柱浓度的空间分布,整个外场观测期间,HCHO的反演误差低于6%。结果表明,车载被动DOAS系统在快速获取化工园区甲醛空间分布信息上可以发挥重要作用,为城市大气中甲醛的立体监测提供了一种有效测量手段。     

Surface heterogeneity of polysiloxane xerogels functionalized by 3-aminopropyl groups

DRIFT spectra of xerogels synthesized by co-condensation of tetraethoxysilane (or 1,2-bis(triethoxysilyl)ethane) and 3-aminopropyltriethoxysilane have been measured using termoevacuation in the temperature range 50-350 °C. The disappearance of bands related to the vibrations of water molecule with temperature growth and shifts of absorption band related to the deformation vibrations of amino groups to the high-frequency region have been observed. The formation of a new band in the range of 3650-3660 cm⁻¹ has been attributed to stretching vibrations of silanol groups. The simplest change of surface layer composition in the amino-containing xerogels by water removal results in transformation of one type of hydrogen bond to another. The first type is associated with forming of cyclical structure with participation of 3-aminopropyl and silanol groups and water molecule, [≡Si(CH₂)₃H₂N···HO(H)···HOSi≡], the other type is associated with the interaction of amino groups between each other.     

苯海拉明的拉曼光谱和红外光谱研究

测量并分析了盐酸苯海拉明的红外光谱和拉曼光谱。在Raman光谱中, 1001 cm-1出现一个极强峰, 在1030 cm-1和618 cm-1各有一个中等峰,此外,在红外光谱中, 714 cm-1和757 cm-1附近出现极强的吸收峰,认定这个化合物中存在单取代苯。C-N的对称伸缩振动出现在837 cm-1, 1433 cm-1和1470 cm-1分别为CH2和CH3的变形振动, 在红外光谱中, 1020 cm-1处明显的吸收峰属于C-O-C反对称伸缩振动。此外, 测量得到含量为25 mg苯海拉明药片的拉曼光谱与纯苯海拉明的拉曼峰比较一致, 可作为无损快速检测该药物的手段。     

High resolution spectrum of DyO molecule

Emission spectrum of DyO molecule has been photographed under high resolution in the wavelength region 5000 to 6300 A. The observed bands have been arranged into three different band systems. The rotational structure in the (0, 0) band of system I is partially resolved and analysed. Isotopic shifts have been calculated for various isotopic molecules and compared with observations. Electronic states involved in the transitions have been discussed.     

On the absorption saturation in the vibrational-rotational bands of molecules

Analytical expressions describing saturation of the stationary absorption coefficient in a vibrational-rotational band in the spectrum of a molecular gas are obtained taking into account that many other bands are involved in the absorption process as well. The formulas are derived for an arbitrary spectral composition of the pumping radiation with an allowance for a difference between the rotational and vibrational relaxation rates and between the relaxation rates of the lower and upper vibrational levels. The influence of saturation on the appearance of the partial inversion and the negative absorption effects is considered. The general formulas are simplified and the vibrational and rotational contributions to the saturation are separated within the frame-work of the local Elsasser model for the rotational band structure. Explicit relationships between the dimensionless parameters describing the vibrational and rotational saturation mechanisms are obtained and analyzed, and conditions under which one of these mechanisms is dominating are determined. Particular calculations were performed for the (000)–(010) and (000)–(001) absorption bands of the O₃ molecule and features of the saturation effect in these bands were established.     

Observation of signature inversion in the πh9/2(×)νi13/2 oblate band

High-spin states in 190Tl have been studied via the 160Gd(35Cl, 5nγ) reaction. The level scheme, consisting of the πh9/2(×)νi13/2 oblate band and a cascade with character of single particle excitations, has been established. Spin values have been firmly assigned to the oblate band in 190Tl, resulting in low-spin signature inversion in the πh9/2(×)νi13/2 oblate band for the first time. Based on the similarity of the level structure in doubly odd Tl nuclei, spin values for the oblate bands in 192―200Tl should be re-assigned, and a consistent low-spin signature inversion has occurred in these oblate deformed nuclei. The low-spin signature inversion phenomena can be interpreted qualitatively by using the 2-quasiparticle plus rotor model including p-n residual interactions.     

Fourier Transform Infrared Spectra of CH(2)DF: The nu(5) and nu(6) Bands

Results of a high-resolution infrared study of the spectroscopy of monodeuterated methyl fluoride, CH(2)DF, are reported for the first time. Spectra ranging from 500 to 3300 cm(-1) have been obtained and cover all the fundamental bands at resolutions down to 0.005 cm(-1). The two lowest energy fundamentals, the nu(5) and nu(6) bands, have been analyzed in detail. Since the molecule has C(s) symmetry, in principle both these bands are AB hybrids, since they belong to the irreducible representation A'. However, it was found that both are almost pure A-type bands. A total of 597 A-type lines of the nu(5) band and 619 A-type lines of the nu(6) band have been assigned. Vibrational and rotational spectroscopic constants have been determined by least-squares fitting to the data. An improved band center for nu(7) is also reported. Copyright 2001 Academic Press.     

Dirac point degenerate with massive bands at a topological quantum critical point

The quasilinear bands in the topologically trivial skutterudite insulator CoSb(3) are studied under adiabatic, symmetry-conserving displacement of the Sb sublattice. In this cubic, time-reversal and inversion symmetric system, a transition from trivial insulator to topological point Fermi surface system occurs through a critical point in which massless (Dirac) bands appear, and moreover are degenerate with massive bands. Spin-orbit coupling, while small due to the type of band character, coupled with tetragonal strain opens the gap required to give the topological insulator. The mineral skutterudite (CoSb(3)) is very near the critical point in its natural state.     

耦合京津冀气溶胶模式的HJ-1卫星CCD数据大气校正

针对目前HJ-1 CCD大气校正没有考虑中国地区气溶胶模式的问题,提出一种耦合中国地区局部气溶胶模式的大气校正方法。以京津冀地区作为研究区域,该方法对地基北京城区和香河站点反演的气溶胶模式参数进行聚类,得到京津冀地区具有代表性的四类气溶胶模式,并根据四类气溶胶模式来建立查找表进行气溶胶光学厚度的反演。HJ-1 CCD数据没有短波红外波段(2.12 μm),无法采用MODIS的气溶胶算法中获得地表反射率的方法来计算蓝红波段的反射率,本文在气溶胶光学厚度的反演中采用HJ-1卫星的蓝色(0.43~0.52 μm)和红色(0.63~0.69 μm)波段的反射率比值作为误差方程的依据,不需要输入地表目标的反射率。基于反演后的光学厚度对HJ-1 CCD数据进行大气校正,并与ASD光谱辐射计测量数据以及MODIS地表产品数据(MOD09)进行对比。结果表明,该方法得到的大气校正结果与ASD测量结果接近,并与MOD09有较强的相关性,红色波段的平均相关系数达到了0.8以上,受气溶胶影响最大的蓝色波段平均的相关系数也达到了0.75左右。     

a-Si:H films: Influence of P- and B-doping on infra-red absorption bands

Summary The infra-red spectra of P- and B-doped hydrogenated amorphous silicon films grown by means of an evaporation method have been measured. The SiH _n stretching and wagging (or rocking) absorption bands have been examined by varying the dopant content measured by Auger analysis. On increasing the doping, a reduction of hydrogen content has been noticed with an enhancing of zeroth-order moment of Si-H stretching at the expense of the Si-H₂ one. Analogous results for B-doped films have been observed. Since no frequency shift towards higher frequencies of the stretching bands has been measured, the observed changes of the intensity of the bands have been attributed to structure modifications rather than to variations in the electronegativity in the neighbours of the silicon atom. In particular, the monohidride configuration with an overall decrease in the number of defects seems to be favoured by the deposition technique adopted. This work was supported in part by GNSM-CNR, M.P.I. and CNR ?Progetto Finalizzato Energetica?.     

The improvement of cross-calibration of IIM data and band selection for FeO inversion

Chang’E-1 (CE-1) Interference Imaging Spectrometer (IIM) dataset suffers from the weak response in the near infrared (NIR) bands, which are the important wavelength for retrieving the minerals and elements of the Moon. In this paper, the cross-calibration was implemented to the IIM hyperspectral data for improving the weak response in NIR bands. The results show that the cross-calibrated IIM spectra were consistent to the Earth-based telescopic spectra, which suggests that the cross-calibration yields acceptable results. For further validating the influence of the cross-calibration on the FeO inversion and searching the optimal bands to retrieve lunar FeO contents, four band selection schemes were designed to retrieve FeO using the original and cross-calibrated IIM spectra. By comparing the distribution patterns and histograms of the IIM derived FeO contents with the Clementine derived FeO, the IIM 891 nm band after cross-calibration showed a higher accuracy in the FeO inversion, hence most useful for lunar FeO inversion.     

Evidence for second-phonon nuclear wobbling

The nucleus 163Lu has been populated through the reaction 139La(29Si,5n) with a beam energy of 157 MeV. Three triaxial, strongly deformed (TSD) bands have been observed with very similar rotational properties. The first excited TSD band has earlier been assigned as a one-phonon wobbling excitation built on the lowest-lying (yrast) TSD band. The large B(E2)(out)/B(E2)(in) value obtainable for one of four observed transitions between the second and first excited TSD bands is in good agreement with particle-rotor calculations for a two-phonon wobbling excitation.     

Excitation of lowest electronic states of the uracil molecule by slow electrons

The excitation of lowest electronic states of the uracil molecule in the gas phase has been studied by electron energy loss spectroscopy. Along with excitation of lowest singlet states, excitation of two lowest triplet states at 3.75 and 4.76 eV (±0.05 eV) and vibrational excitation of the molecule in two resonant ranges (1?C2 and 3?C4 eV) have been observed for the first time. The peak of the excitation band related to the lowest singlet state (5.50 eV) is found to be blueshifted by 0.4 eV in comparison with the optical absorption spectroscopy data. The threshold excitation spectra have been measured for the first time, with detection of electrons inelastically scattered by an angle of 180°. These spectra exhibit clear separation of the 5.50-eV-wide band into two bands, which are due to the excitation of the triplet 1³ A?? and singlet 1¹ A?? states.     

Thermal Emission Spectrum of the Cobalt Monobromide Molecule

ABSTRACT

The thermal emission spectrum of the CoBr molecule has been photographed for the first time in the spectral region 4200–6000 Å using the high-temperature excitation technique and the 2-meter plane grating spectrograph (PGS-2). The spectrum has been recorded at a reciprocal linear dispersion of 7.3 Å/mm. About 203 red degraded and line-like bands have been recorded, out of which 172 are entirely new. The observed bands have been classified into 31 systems, of which 23 are entirely new. The vibrational analyses have been carried out using band head measurements and the Deslandre table. The ground state of the CoBr molecule is found to be ³Φ with the vibrational constants 318.3, 329.5, and 332.7 cm^?1.     

The effects of internal rotation on some infrared and electronic band contours of tetrolaldehyde

Contour calculations are reported for one electronic band and three infrared bands of tetrolaldehyde, CH₃CCCHO, where the methyl group executes relatively free internal rotation with respect to the body of the molecule. The electronic band described, the 0-0 band of the π^∗ ← n transition near 3760 Å, has the transition moment located in the molecular frame. The infrared bands are the 3 degenerate perpendicular bands of the methyl group, having the transition moments localized in the rotating group. Gross differences in contour are observed in the two types of bands.     

Infrared and raman spectra of barium nitrite monohydrate

The low temperature infrared absorption and room temperature laser Raman spectra of polycrystalline Ba(NO₂)₂ · H₂O and its deuterated analogue are studied. The strongly bonded H-atom of the water molecule makes a highly bent H-bond while the weakly bonded H-atom exhibits a slightly bent (or possible bifurcated) bond consistent with recent structural data; the H-bond enthalpies are estimated to be 3.3 and 2.1 $\text{KCal}\text{mole}$ respectively. The wagging, twisting and rocking modes of the water molecule have been assigned using several well known criteria. The force constants of these modes have also been computed. The librational splittings observed at low temperature are consistent with polarization data, and are being attributed to infrared active factor group components.