首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
High-resolution vibration-rotation spectra of gas-phase deuterobromoacetylene have been recorded in the 240-990 cm-1 infrared region. The analyzed band systems are rich in hot bands and have a high density of lines. Five band systems and a total of 124 vibration-rotation bands of the isotopic species DCC79Br and DCC81Br have been rotationally analyzed. Accurate rotational parameters and vibrational wavenumbers for 33 vibrational states of each species have been obtained from the rotational analysis. l doubling and rotational l resonance have been observed on some states and the respective resonance parameters have been obtained through nonlinear least-squares optimization. A Fermi resonance block model with perturbation terms has been used for the analysis of the vibrational states. With optimized parameters, the model produces root-mean-square deviations of observed - calculated wavenumbers of about 0.3 cm-1 for both isotopic species. Copyright 1999 Academic Press.  相似文献   

2.
High-resolution spectra of H216O were recorded with a Fourier-transform spectrometer covering transitions in the (020)-(010), (100)-(010), and (001)-(010) bands from 1100 to over 2300 cm-1. Also included in the study were previously reported measurements of these bands and measurements of the (020)-(000), (100)-(000), and (001)-(000) bands from 2620 cm-1 to 4500 cm-1. The linestrengths were fitted to a model which takes into account the interactions between the vibrational states (020), (100), and (001). The model included dipole moment matrix elements (also referred to as transition elements) represented by 19 expansion coefficients for B-type transitions and 14 expansion coefficients for A-type band transitions. The most satisfactory results were obtained when the relative signs and values of the leading dipole moment terms of each of the three "hot" bands were as follows: u(020-010) = 1.936(97) x 10(-1) D, u(100-010) = 3.876(19) x 10(-2) D, and u(001-010) = 2.523(75) x 10(-2) D. Hot water emission experimental frequencies from other studies were included in an analysis to obtain rotational energies for levels up to high J and/or Ka of the (020), (100), and (001) vibrational states. The results from this study provide a more accurate representation of the parameters than those available at present for the six bands. Copyright 1999 Academic Press.  相似文献   

3.
Spectra of a natural sample of hydrogen telluride as well as a spectrum of monoisotopic H2 130Te have been recorded by means of Fourier transform spectrometry with a resolution of 0.003 cm-1 in the spectral domain 7.5-4.3 μm where it is easy to observe the main absorbing bands nu1 and nu3. We have located and assigned for the first time the 2nu2 band which appears in the lower wavenumber range of the recorded spectral domain near 1700 cm-1. It proved necessary to treat simultaneously the three states (020), (100), and (001). nu1 and nu3 are indeed Coriolis-coupled vibration-rotation bands and it was observed that a few rotational levels of (001) could not be fitted to within their experimental accuracy without considering the second-order Coriolis interaction between the rotational levels of (020) and (001). In this way all the experimental levels were calculated to within the experimental uncertainty, and precise sets of vibrational energies and rotational and coupling constants were obtained for the seven most abundant H2Te isotopic species, namely H2 130Te, H2 128Te, H2 126Te, H2 125Te, H2 124Te, H2 123Te, and H2 122Te. For the most abundant isotopic species H2 130Te the bands centers arenu0 (2nu2) = 1715.9568, nu0 (nu1) = 2065.2709, nu0 (nu3) = 2072.1101 cm-1. Copyright 1997Academic Press  相似文献   

4.
We have recorded the infrared absorption spectrum of pyrrole at 0.005 cm-1 spectral resolution using a Fourier transform interferometer. The rotational analysis of the symmetric out-of-plane C-H bend 22(1)0 fundamental band at 722.132993(5) cm-1 was performed, allowing 6760 lines to be assigned. These lines were fitted simultaneously to literature data on nu1 [A. Mellouki, R. Georges, M. Herman, D. L. Snavely, and S. Leytner, Chem. Phys. 220, 311-322 (1997)] and microwave lines [G. Wlodarczak, L. Martinache, J. Demaison, and B. P. Van Eijck, J. Mol. Spectrosc. 127, 200-208 (1988)]. A set of rotation parameters was determined for the ground state in Ir and IIIr representations, together with vibration-rotation constants for the v1 = 1 and v22 = 1 vibrational states. The fine structure in the strongest of the hot bands in that range was highlighted by division, from the experimental data, of the spectrum of the 22(1)0 band, computed using the vibration-rotation parameters. The rotational assignment of 930 lines in the strongest hot band was performed. The 22(1)024(1)1 vibrational assignment is proposed, leading to x22,24 = 1.90 cm-1. The transition dipole matrix element for the 22(1)0 band is estimated to || || = 2 x 10(-4) D. Copyright 1999 Academic Press.  相似文献   

5.
Using a high-resolution (R = 0.0025 cm-1) Fourier transform spectrum of nitric acid recorded at room temperature in the 1100-1240 cm-1 region, it has been possible to perform a more extended analysis of the nu8 + nu9 band of HNO3 centered at 1205.7075 cm-1. As in a recent analysis of this band [W. F. Wang, P. P. Ong, T. L. Tan, E. C. Looi, and H. H. Teo, J. Mol. Spectrosc. 183, 407-413 (1997)], the Hamiltonian used for the line positions calculation takes into account, for the upper state, the DeltaK = +/-2 anharmonic resonance linking the rotational levels of the v8 = v9 = 1 "bright" vibrational state and those of the "dark" v6 = v7 = 1 vibrational state. More than 4800 lines were assigned in the nu8 + nu9 band, which involve significantly higher rotational quantum numbers than in previous works. On the other hand, and surprisingly as compared to previous studies, the nu8 + nu9 band appears to be a hybrid band. In fact, nonnegligible B-type transitions could be clearly identified among the much stronger A-type lines. Accordingly, a set of individual line intensities were measured for lines of both types and were introduced in a least-squares fit to get the A- and B-type components of the transition moment operator. Finally, a synthetic spectrum of the 8.3-μm region of HNO3 has been generated, using for the line positions and line intensities the Hamiltonian constants and the expansion of the transition moment operator which were determined in this work. In this way, the B-type and the A-type components of the nu8 + nu9 band appear to contribute for about (1/4) and (3/4), respectively, to the total band intensity. Copyright 1999 Academic Press.  相似文献   

6.
Line positions and line intensities of the nu1, nu3, and 2nu4 bands of 14NH3 were analyzed using line positions from 0.0054 cm-1 apodized resolution FT spectra recorded at Orsay and using line intensities from 0.011 cm-1 unapodized resolution FT spectra recorded at Kitt Peak National Observatory. About 2110 lines with J' 相似文献   

7.
The infrared spectrum of vinyl fluoride (CH2=CHF) has been investigated in the region 390-590 cm-1 at room temperature and at a resolution of 0.0016 cm-1 using a Fourier transform spectrometer. The rovibrational analysis of the spectral features allowed us to assign about 11 000 lines (J 相似文献   

8.
The two triad systems of hydrogen sulfide (2nu2, nu1, and nu3 near 4 μm and 3nu2, nu1 + nu2, and nu2 + nu3 near 2.7 μm) were analyzed using 14 spectra recorded at 0.0056 and 0.011 cm-1 resolution with the McMath Fourier transform spectrometer located at Kitt Peak National Observatory. Experimental upper state levels of H232S, H234S, and H233S were obtained from assigned positions (as high as J = 20 and Ka = 15 for the main isotope). These were fitted to the A-reduced Watson Hamiltonian to determine precise sets of rotational constants through J10 and up to nine Fermi and Coriolis coupling parameters. Intensities of the two H232S triads were modeled with rms values of 2.5%, using the transformed transition moment expansion with 19 terms for 568 intensities of the first triad and 11 terms for the 526 intensities of the second triad. The second derivatives of the dipole moment with respect to normal coordinates were estimated in Debye to be: 22μx = -0.004873 (90); 12μx = 0.01372 (30); and 23μz = 0.01578 (30). This confirmed that for hydrogen sulfide some of the second derivatives are larger than the first derivatives. The calculated line intensities were summed yielding integrated band strengths (in cm-2/atm at 296 K) as follows: 0.3315 for 2nu2, 0.4522 for nu1, 0.1201 for nu3, 0.0303 for 3nu2, 1.820 for nu1 + nu2, and 2.869 for nu2 + nu3. In addition, the hot band transitions were identified in both regions. Finally, a composite database of hydrogen sulfide line parameters was predicted for the 5- to 2.5-μm region. Copyright 1998 Academic Press.  相似文献   

9.
The very weak bands nu1 + 2nu2 + 3nu3 and 4nu1 + nu3 of 16O3 have been observed for the first time, using the Fourier transform spectrometer (FTS) of Reims and the usual experimental setup providing a large product p x l of approximately 38 Torr x 36 m. The upper levels of these A-type bands which are rather close in energy (they appear respectively at 5291.722 and 5307.790 cm-1) belong to two different sets of interacting polyads. To correctly reproduce the rotation-vibration energy levels and account for the observed perturbations, both bands are treated in a dyad approximation: the (123) state in the Coriolis resonance with the (330) state, and the (401) state in the Coriolis resonance with the (024) state. The assignments of the rotation-vibration levels of the (123) state are confirmed by measurements of line positions of the hot band nu1 + 2nu2 + 3nu3 - nu2 which has also been observed for the first time. The fits are very satisfactory: the r.m.s. deviation for 249 energy levels of the (123) state is 2.4 x 10(-3) cm-1 and is 2.0 x 10(-3) cm-1 for 266 levels of the (401) state. These r.m.s. are near experimental accuracy. Transition moments for the three observed bands are determined from measured line intensities. Copyright 1997 Academic Press. Copyright 1997Academic Press  相似文献   

10.
The dispersed fluorescence spectrum of lines in the 460 nm band system of NiCl2 (nickel dichloride) is presented. The fluorescence was pumped on single rotational transitions of two spin components in a vibrational band observed previously in the laser excitation spectrum. Fluorescent transitions to levels of the &Xtilde;3Sigma-g (ground) state are assigned and discussed. The spectra also show clear evidence for a previously unidentified low-lying electronic state, assumed to be the ? state, which lies about 2000 cm-1 above the ground state. This is likely to be of 3Pig character and is discussed on that basis. The wavenumber of the symmetric stretching vibration of NiCl2 in the ? state is determined to be 367 cm-1, slightly larger than the &Xtilde; state value (360 cm-1). Copyright 1998 Academic Press.  相似文献   

11.
The Fourier transform infrared spectrum of H3SiI has been recorded in the nu1/nu4 region from 2075 to 2315 cm-1 at an optical resolution of 2.3 x 10(-3) cm-1. The nu1/nu4 fundamental bands and the (nu1 + nu3) - nu3/(nu4 + nu3) - nu3 hot bands have been rotationally investigated. Numerous local perturbations have been observed in the nu1 and nu4 bands and in the hot bands. Without the lines involved in perturbations, more than 2900 transitions of the nu1/nu4 bands were used to determine the band origins and the vibration-rotation parameters of the nu1 = 1 and nuv4 = 1 states. A least-squares fit of 766 apparently unperturbed transitions of the hot bands gave the parameters of the nu1 = nu3 = 1 and nu4 = nu3 = 1 states. The l(2, 2) resonance in nu4 and the A1-E Coriolis coupling between nu1 and nu4 have been investigated. Most of the local perturbations have been studied individually using a simple model by which the main perturber for each resonance was identified. Copyright 1998 Academic Press.  相似文献   

12.
Infrared spectra of 16O12C17O, 17O12C17O, and 17O12C18O in a carbon dioxide sample enriched with oxygen-17 have been recorded with a resolution of about 0.0025 cm-1 in the regions of the fundamental bands, nu2 (600-800 cm-1) and nu3 (2200-2400 cm-1), and in the region of the "forbidden" band, nu1 (1200-1400 cm-1), using the long path difference Fourier transform spectrometer of the LPMA in Paris. For each species, the first hot band in the 4.5-μm region and two hot bands at least in the 15-μm region have been studied for the first time, and a simultaneous reduction of wavenumbers measured in different spectral regions has been carried out yielding new or improved spectroscopic constants. Line intensities have been measured in the region of the nu2 and nu3 bands of 16O12C17O, and the corresponding rotationless transition dipole moments and Herman-Wallis coefficients have been reported. Copyright 1998 Academic Press.  相似文献   

13.
High-resolution FTIR spectra of monoisotopic D3Si35Cl have been recorded in the regions 440-590 cm-1 (nu3/nu6) and 900-1100 cm-1 (2nu6/nu3 + nu6/2nu3). A detailed rovibrational study was done for the 2nu06, 2nu-/+26, and 2nu3 overtone bands and for the 2nu+/-26-nu+/-16, 2nu06-nu-/+16, and (nu3 + nu+/-16)-nu+/-16 hot bands. For the first time the interactions occurring between the v6 = 2, v3 = v6 = 1, and v3 = 2 levels of any trideuterated silyl halide have been analyzed. The (nu3 + nu+/-16)-nu+/-16 hot band served to obtain accurate energies of the v3 = v6 = 1 level, the nu3 + nu6 combination band not being detectable on our spectra. The first experimental determination of A0 and D0K for this molecule was undertaken by a well-established method, using the nu6, 2nu+/-26-nu+/-16, and 2nu-/+26 bands. Ground state energy differences DeltaK(J) = E0(J, K) - E0(J, K - 3) were calculated for K values from 2 to 16. By a least-squares fit of 163 such differences, the A0 and D0K values thus obtained were (in cm-1): A0 = 1.4278230(8) and D0K = 5.3916(31) x 10(-6). Copyright 1999 Academic Press.  相似文献   

14.
Fourier transform spectrometer data of heavy water vapor were obtained at resolutions of 0.01 and 0.02 cm-1. The spectra were analyzed to obtain line center frequencies and line strengths of HD16O from 4719 to 5843 cm-1. The analysis included 1700 assigned lines of the (011)-(000), (200)-(000), (120)-(000), and (021)-(010) bands. This is the first report of assignments in the weak (120)-(000) band which borrows much of its strength from the (200)-(000) band. The measurements provided in this work are a marked improvement over the HDO listing presently available on the HITRAN database in the spectral region. Copyright 1997 Academic Press. Copyright 1997Academic Press  相似文献   

15.
分析了S355JR和S355J2低碳钢(/%:0.17~0.20C、0.30~0.55Si、1.40~1.60Mn、≤0.020P、≤0.015S、0.020~0.040A1、0.020~0.030Nb)28~40 t钢锭轧成230~400 mm钢板出现的开裂和穿孔缺陷。通过提高浇钢工操作水平,根据钢水过热度控制本体浇铸和帽口浇铸时问;控制精炼终点[O]≤25×10-6以及钢中铝含量0.020%~0.040%等优化浇铸工艺措施使钢锭探伤合格率提高到96.8%。  相似文献   

16.
The filamentous virus fd consists of a single-stranded DNA genome sheathed by 2700 copies of a 50-residue alpha-helical subunit (protein pVIII) and serves as a model assembly of alpha-helices. To advance vibrational assignments for the alpha-helix, we have investigated Raman spectra of fd virions containing 13C and 2H (deuterium) labels at various main-chain sites of the pVIII subunits. 13C was introduced at specific peptide carbonyls, while deuterium was introduced at selected alpha-carbon (Calpha) and amide nitrogen positions. Interpretation of the Raman spectra reveals a previously unrecognized alpha-helix band in the spectral interval 730-745 cm-1, tentatively assigned to a carbonyl in-plane bending mode (amide IV). Experimental evidence has also been obtained for a distinctive alpha-helix marker near 1345 cm-1, assigned to a coupled Calpha-H bending and Calpha-C stretching mode. The fd virions containing 13C-labeled carbonyls exhibit unexpectedly complex amide I profiles, consisting of multiple band components. Amide I splitting resulting from 13C substitution of carbonyls is attributed to decoupling of transition-dipole interactions normally occurring in the extended pVIII helix. The present study identifies novel conformation-dependent Raman bands in a native alpha-helix assembly, confirms amide I and amide III assignments proposed previously for filamentous viruses, and facilitates new Raman assignments for the packaged ssDNA. The alpha-helix markers identified here should also be useful in conformation analyses of other proteins by Raman spectroscopy.  相似文献   

17.
Laser excitation spectra of gaseous CoO have been recorded using Doppler-limited intracavity spectroscopy and supersonic jet-cooled molecular beam methods. As seen in the molecular beam spectra there are nearly 100 bands arising from the X4Delta7/2 spin component of the ground state in the wavelength region 430-720 nm. All of them are very strongly red-degraded and most of them are perturbed. 59Co hyperfine broadenings or splittings have been observed in many. The bands can be arranged into five electronic transitions, together with a considerable number of "extra" bands induced by perturbations; two of the excited electronic states are 4Phi, while the other three, which lie within 1700 cm-1, are 4Delta. Semi-empirical calculations have been carried out for the 4Delta excited states, using exchange integrals transferred from the TiO and VO spectra; the predicted energies, spin-orbit structures, and relative intensities in absorption are consistent with the assignment of all three 4Delta states to the same electron configuration, (4ssigma)1(3ddelta)3(3dpi)2(3dsigma)1. It seems that there are extensive interactions between the excited 4Delta states, because only one of them gives rise to a recognizable, though irregular, long vibrational progression in absorption. The other two progressions die out abruptly and unexpectedly after three or four members, presumably as a result of interference effects; however, wavelength-resolved fluorescence studies, together with calculations of the Franck-Condon overlap integrals to the various vibrational levels of the ground state, show that the upper state progressions reappear following a region of confused absorption. All of the excited states show highly irregular variations of their vibrational intervals and rotational constants with the vibrational quantum number, v. The wavelength-resolved fluorescence spectra give evidence for new low-lying electronic states of CoO at 3038, 5989, and 9105 cm-1; based on its vibrational frequency the 3038 cm-1 state is possibly the sigmadelta4pi2 B4Sigma- state. Copyright 1997 Academic Press. Copyright 1997Academic Press  相似文献   

18.
With an infrared diode laser spectrometer in pulse mode we studied the N2 broadening of H2S absorption lines in the nu1, nu2, and nu3 bands. Altogether 22 lines were investigated: 16 lines from the R branch of the nu1 band (3 相似文献   

19.
研发的耐候钢S355J2W(/%:0.06~0.10C,0.20~0.40Si,1.00~1.30Mn,≤0.008S,≤0.020P,0.25~0.40Cu,0.30~0.55Cr,0.10~0.30Ni,0.020~0.040Nb,0.020~0.050Alt)的试生产流程为铁水-120 t顶底复吹转炉-LF-250 mm×2 000 mm板坯连铸-轧制≤16 mm板。通过采取控制转炉终点[C]≤0.05%,[P]≤0.015%,精炼时(FeO)+(MnO)≤1.5%,(SiO2)≤15%,精炼渣碱度≥3.0,[Al]s≥0.025%,按Ca/Al=0.06~0.12,喂入钙线,连铸时采用耐候钢专用保护渣[主要成分/%:34.0CaO,28.0SiO2,4.6Al2O3,≤6(Li2O+B2O3)],控制开坯温度1 010~1 060℃等工艺措施,≤16 mm耐候钢S355J2W成品板铝含量为0.025%~0.035%,钢中平均氧含量为21×10-6,平均氮含量为31×10-6,钢中非金属夹杂物的尺寸基本≤14μm,各项冶金质量指标合乎要求。  相似文献   

20.
The hot bands accompanying the fundamentals nu6 and nu3 of CH3NC in the region 1300-1560 cm-1 observed in high-resolution Fourier transform recordings complemented by diode laser spectra have been analyzed. The observed transitions comprise 16 subbands of the pair of perpendicular E-E bands nu6± + nu8± - nu8± and nu7-/+ + 2nu80 - nu8± whose upper states form a Fermi dyad, 18 subbands of the A1,2-E perpendicular bands nu6-/+ + nu8± - nu8±/nu7± + 2nu8±2 - nu8± with upper states forming another Fermi dyad, and 8 subbands of the bi-parallel E-E band nu3 + nu8± - nu8±. The anharmonic, Coriolis, and l-type interactions which couple these upper states with each other and with the states nu7-/+ + 2nu8±2, nu4 + 3nu8±1, and nu4 + 3nu8±3 have been included in an 18 x 18 Hamiltonian matrix whose eigenvalues model the upper levels of the observed transitions. The values of 46 upper state spectroscopic constants and interaction constants have been adjusted by least squares to 950 observed lines. The results provide a reliable quantitative picture of the interacting states and yield accurate values for the spectroscopic constants of the various states and for the anharmonic constants x68, x68 (g68), and x38. Copyright 1997Academic Press  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号