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1.
A combined analysis of the A2Πi → X2Σ+ and B2Σ+ → X2Σ+ band systems of AlO, involving 21,500 line assignments, has been performed. The analysis indicates that the previously reported γ values of the B2Σ+ state are questionable. The present analysis shows that γ(B2Σ+) ≈ 0.014 cm−1, essentially independent of the vibrational level. The positive sign is consistent with second order interaction with the higher-lying C2Πr and lower-lying A2Πi states. It also appears that many of the previously reported γ and γD values of X2Σ+ (v > 0) are doubtful. In fact, γ(X2Σ+) is observed to become increasingly negative for v″ > 1, due to second order interaction with the low-lying A2Πi state. The present results are based on models where the hyperfine structure of the 2Σ+ states has been taken into account explicitly. Intensity patterns of the branches of the B2Σ+ → X2Σ+ system have been shown to be influenced by the case bβS coupling in the ground state v = 0,1 levels. This gives rise to intensity differences of around 10 percent in the R1/R2 and P1/P2 doublet components. The synthesized intensity patterns are fully in accord with the F1/F2 assignments of the present work. 相似文献
2.
Doppler-limited vib-rotational absorption spectra of the A ← X electronic transition of I35/37Cl are measured in the range 11,352-13,507 cm−1 using a Ti:sapphire ring laser. The P-, Q-, and R-branch lines belonging to the v ← v″ = (0-7) ← (0-7) transition in I35Cl and the v ← v″ = (0-6) ← (2-6) transition in I37Cl are assigned. Under Doppler-limited conditions, the P- and R-branch lines are split into doublets by the nuclear quadrupole coupling effect of the I atom. The unperturbed positions of these lines are correctly calculated, whereas splitting in the Q-branch lines was not observed. The mass-reduced Dunham expansion coefficients Ul,m of the A and X states and the spectroscopic constants , and Hv′ of the A state are determined using a global least-squares fitting procedure. 相似文献
3.
The direct observation and rotational analysis of the (3, 6) band in the comet-tail (A2Πi-X2Σ+) system of CO+ are carried out for the first time employing optical heterodyne and magnetic rotation enhanced velocity modulation spectroscopy. That 193 lines are assigned to this band ranging from 12 100 to 12 370 cm−1 results in most accurate molecular constants by nonlinear least-squares fitting procedure employing the effective Hamiltonians. 相似文献
4.
The present work puts forward the results of the recordings carried out under high resolution by conventional, photographic spectroscopy and modern analysis of thirteen bands with v′ = 7-12 and v″ = 16-24 of the fourth-positive (A1Π → X1Σ+) band system. The current investigations include the region of the observed 13C16O molecule spectrum, much greater now than before. Especially, new transitions connected with not hitherto observed v′ = 12 vibrational level of the A1Π state, were recorded and studied. Moreover, the region of perturbations observed in the upper state of the fourth-positive system was significantly enlarged. The observed perturbations were confronted with those predicted from theoretical calculations. 相似文献
5.
Randall H. Skelton Chris D. Boone Peter F. Bernath Bernard Pinchemel 《Journal of Molecular Spectroscopy》2003,219(1):1-12
The A′1Π-X1Σ+ near infrared system of strontium oxide (SrO) was observed at high spectral resolution by measuring the chemiluminescence from a Broida flow reactor using a Fourier transform spectrometer. In total, 32 bands from , , were measured within the spectral region at a resolution of . Vibrational levels of the upper state were observed up to vA′=4, and more than 5600 rotational lines were assigned. Incorporating previously published high resolution data for the A1Σ+-X1Σ+ system, a global fit to both data sets yields improved Dunham constants for the ground state and for the lower vibrational levels (vA′=0, 1, and 2) of the A′1Π state. Because perturbations arising from interactions with the b3Σ+ and A1Σ+ states affect the higher vibrational levels of the A′1Π state more strongly, levels vA′=3 and 4 were represented by effective band constants in the fits. RKR potentials for the X1Σ+,A′1Π, and b3Σ+ states have been generated utilizing all the available data, Franck-Condon factors have been calculated for the A′1Π-X1Σ+ system, and A′1Π∼b3Σ+ and A′1Π∼A1Σ+ perturbations are discussed. 相似文献
6.
Natural germanium and selenium consist of, respectively, five and six stable isotopes. Several of these isotopes have considerable abundances and one should expect to observe the bands of at least six isotopic variants of germanium monoselenide (GeSe). In this paper, for the first time, the results of the high-resolution electronic spectrum of the main transition A1Π-X1Σ+ of the specific isotopomer 74Ge80Se, excited in a microwave discharge and recorded in the 33 500-26 000 cm−1 region using a Fourier transform spectrometer, is discussed. From the rotational analysis of 25 bands involving v″ = 0-12 and v′ = 0-7, accurate vibrational and rotational constants of the A1Π state are determined. The present study has revealed perturbations in the v′ = 6 and 7 levels of the A1Π state. 相似文献
7.
The B2Σ+ → X2Σ+ (0-1, 2, 3, 4 progression) electronic transition of 12C17O+ was first observed and analyzed by Szajna and Ke¸pa [Spectrochim. Acta A 65 (2006) 1014-1020]. We have now extended our previous studies. The use of high resolution conventional spectroscopic techniques has allowed first rotational analysis of the 1-2, 1-3, 1-4 and 1-5 bands of the first negative system in the 37,000-43,000 cm−1 spectral region. Approximately 500 transition wavenumbers were measured with an estimated accuracy of 0.005 cm−1. The present data were combined with the previous measurements to yield an improved set of molecular constants for the B2Σ+(v′ = 0, 1) and X2Σ+(v″ = 1, 2, 3, 4, 5). The v′ = 1 and v″ = 5 vibrational levels were observed for the first time and the main molecular constants are (in cm−1, one standard deviation in parentheses)
B2Σ+ X2Σ+ B1 = 1.710792(20) B5 = 1.825694(23) D1 = 7.799(15) × 10−6 D5 = 6.085(21) × 10−6 γ1 = 1.9491(37) × 10−2 γ5 = [8.381] × 10−3 - Full-size table
8.
The spectrum of CS+ cation was recorded in the 12,235-12,600 cm−1 region by employing optical heterodyne velocity modulation absorption spectroscopy. In combination with simultaneous measurement of optical heterodyne concentration modulation absorption spectroscopy, the spectral lines of CS+ blended with the neutral CS lines were identified and extracted from the observed spectra. One hundred and eighty-two spectral lines of CS+ were assigned to the (2, 1) band in the A2Пi-X2Σ+ system and the improved molecular constants of the upper level (υ = 2) in the A2Пi state were derived by nonlinear least squares fitting. 相似文献
9.
The X2Π electronic ground states of NCO and CNO have been investigated by complete ab initio methods. The dependence of the Renner-Teller parameters, ? and , on the ab initio method and on the basis set have been studied. These parameters have also been compared to experimental data for NCO. The potential energy surfaces of the X2Π state have been determined by the MRCI method and the cc-pVQZ basis set for NCO and CNO. The rovibronic levels of both isomers have been calculated variationally up to approximatively 4000 cm−1 for J ? 5/2 and K ? 2, with the inclusion of the geometry dependence of the spin-orbit coupling. The agreement with experimental data obtained for NCO is remarkable. A similar accuracy for the ab initio rovibronic levels of CNO is expected since no experimental data exists for this isomer. 相似文献
10.
Transitions between the spin-rotational levels of the 12CH radical in the v = 1 level of the X2Π state have been studied by the technique of laser magnetic resonance at far-infrared wavelengths. The data have been combined with a measurement of lambda-doubling transition frequencies at 7 GHz to determine an improved set of molecular parameters for CH in the v = 1 level. The parameters provide information on the effects of vibrational excitation on the structural properties of CH. Accurate predictions of the transition frequencies between the low-lying levels of the radical in the absence of a magnetic field have also been made.Small inconsistencies in the least-squares fit of the laser magnetic resonance data prompted re-measurement of three far-infrared laser frequencies, the 122.5 μm line of CH2F2 pumped by 9R(22), the 122.5 μm line of CH2F2 pumped by 9P(8) and the 554.4 μm line of CH2CF2 pumped by 10P(14). The new measurements differ by as much as 3.8 MHz from those made previously and are more accurate; they also remove the inconsistencies in the fit. The re-measured frequencies of the two 122.5 μm lines are identical within experimental error which suggests that the far-infrared lasing transition is the same, namely the rR23(32) transition in the v9=1 level of CH2F2. 相似文献
11.
The (0,0) and (0,1) bands of the C4Σ−-X4Σ− electronic transition of VS (near 809 and 846 nm, respectively) have been recorded at high resolution by laser-induced fluorescence, following the reaction of laser-ablated vanadium atoms with CS2 under supersonic free-jet conditions. A least squares fit to the resolved hyperfine components of the rotational lines gives the rotational constants and bond lengths as C4Σ−: , ; X4Σ−: , . The electron spin parameters for the two states show that there are some similarities between the states of VS and those of VO, but the hyperfine parameters show that the compositions of the partly filled molecular orbitals are by no means the same. The ground state Fermi contact parameter of VS, b(X4Σ−), is only 58% of that of the ground state of VO, which implies that the σ orbital of the ground σδ2 electron configuration has less than 50% vanadium 4s character. Similarly, the excited state Fermi contact parameter, b(C4Σ−), is very much smaller than that of VO. No local rotational perturbations have been found in the C4Σ− state of VS, though an internal hyperfine perturbation between the F2 and F3 electron components at low N confuses the hyperfine structure and induces some forbidden (ΔJ=±2) rotational branches. 相似文献
12.
We use the RENNER program system (see, for example, P. Jensen, G. Osmann, and P. R. Bunker, in “Computational Molecular Spectroscopy” (P. Jensen and P. R. Bunker, Eds.), Wiley, Chichester, 2000, and references therein) to make a detailed calculation of the rovibronic energies in the first excited electronic state, Ã2Π, of the MgNC radical. This calculation is based on ab initio data (supplemented here with points for larger bending displacements from linearity) calculated at the level of MR-SDCI(+Q)/[TZ3P+f(Mg), aug-cc-pVQZ (N and C)] by T. E. Odaka, T. Taketsugu, T. Hirano, and U. Nagashima (J. Chem. Phys.115, 1349-1354 (2001)). These authors employed ab initio derived spectroscopic constants to calculate vibronic energies using perturbation expressions (J. T. Hougen and J. P. Jesson, J. Chem. Phys.38, 1524-1525 (1963)), and their results suggested that an observed vibronic band belonging to the Ã2Π←X?2Σ+ electronic transition (R. R. Wright and T. A. Miller, J. Mol. Spectrosc.194, 219-228 (1999)) should be reassigned. The present work confirms this conclusion, which is further substantiated by the rotational structures calculated in the vibronic states and by Franck-Condon theory predicting relative intensities. 相似文献
13.
14.
Near-infrared emission spectra of the X22Π3/2 → X12Π1/2 fine structure transitions of PbH and PbD have been investigated by high-resolution Fourier-transform spectrometry. The fine structure splitting in the X2Πr ground state of 208PbH was found to be 6924.4926(4) cm−1. Accurate rotational constants for the v = 0 and 1 vibrational levels of the X2Πr states of 208PbH, 207PbH, 208PbD and 207PbD and hyperfine structure constants for the X12Π1/2 states of 207PbH (207PbD) have been derived. 相似文献
15.
Leah C. O’Brien Bradley A. Borchert Sadasivan Shaji Robert W. Field 《Journal of Molecular Spectroscopy》2008,252(2):136-142
The visible electronic spectrum of AuO has been recorded at rotational resolution using intracavity laser absorption spectroscopy. Six vibrational bandheads have been identified, and three of the bands have been analyzed and assigned as bands of a newly identified B2Σ−-X2Π3/2 transition of AuO. The molecular parameters for the newly identified B2Σ− state are presented. 相似文献
16.
Laser excitation spectra of the A2Σ-X2Πi system have been recorded for 63CuS and 65CuS isotopic molecules with a single-mode dye laser operating in the region 17000–18000 cm?1. For highly overlapped sequences, use of a monochromator as a narrow band filter was necessary to allow rotational analysis. A simultaneous fit of all eight analyzed bands has led to the following spectroscopic constants for 63CuS (in cm?1):
State | |||||||
0 | 17924.335 (7) | 0.17989 (4) | 0.177 (7) | 0.03853 (7) | |||
1 | 842.574 (7) | 0.18701 (4) | 0.163 (7) | 0.01496 (9) | |||
0 | 432.566 (6) | 0.18818 (4) | 0.162 (7) | 0.01508 (9) | |||
1 | 411.289 (7) | 0.18724 (4) | 0.184 (7) | ?0.96 (6) | |||
0 | — | 0.18839 (4) | 0.160 (7) | ?0.11 (6) |