共查询到20条相似文献,搜索用时 31 毫秒
1.
Z. Zelinger T. Amano V. Ahrens S. Brünken F. Lewen H.S.P. Müller G. Winnewisser 《Journal of Molecular Spectroscopy》2003,220(2):223-233
Measurements of the rotational spectrum of HCN in excited vibrational states have been extended to higher-J values. The transitions reach J=8←7 around 710 GHz for most vibrational states studied in this investigation and J=22←21 near 2 THz for the (020) and (030) vibrational states. Using a pure sample of gaseous HCN at 350 K, selected states up to one quantum in the C–H stretching vibration at 3311.5 cm−1 have been investigated. Even transitions having two quanta in the C–H stretch could be studied employing a glow discharge in a gas mixture of CH4 and N2. Molecular constants in 13 vibrational states have been obtained, several of which have been studied for the first time by rotational spectroscopy. The vibrational temperature in the discharge system is found to be about 1500 K for the stretching vibrational modes and about 600 K for the bending states. 相似文献
2.
Takayoshi AmanoZdeněk Zelinger 《Journal of Molecular Spectroscopy》2002,211(2):273-278
Submillimeter-wave transitions of HNC are observed in an extended negative glow discharge. The measurements of the rotational lines in the ground state, as well as in the vibrational fundamentals, are extended to higher J values (up to J=9←8 in the 830-GHz region). The lines in the higher vibrational excited states ν2+ν3, 2ν2, and 2ν2+ν3 are also observed and assigned, using the frequency-magnetic field double modulation technique. Dramatic enhancement of the signal intensity strongly suggests that HNC is predominantly produced in the extended negative glow discharge through the dissociative recombination of HCNH+ with electrons. 相似文献
3.
T. Hirao 《Journal of Molecular Spectroscopy》2008,248(1):26-40
The pure rotational transitions of HCO+ in excited vibrational states located below 5000 cm−1 over the ground state have been investigated with a high-sensitivity frequency/magnetic field double modulation submillimeter-wave spectrometer in the frequency range of 280-810 GHz. The ions were generated in an extended negative glow discharge through a gas mixture of a few millitorrs of H2 and CO and 12 mTorr of Ar buffer gas. Throughout the experiments, the cell was maintained at liquid nitrogen temperature. In the present study, we have determined accurate molecular constants for the excited vibrational states. Our analysis suggests that there may be a higher order Coriolis interaction between the (0 3 1) and (1 2 0) states. In previous investigations, the Stark effect caused by the electric field present in the discharge plasma was cited as a reason for non-observations of low-J lines in the (0220) and for the systematic shifts observed for low-J lines in the (0110), (0220), (0310), and (0420) states of HCO+ as well as DCO+. In the present investigation, some low-J lines in the (0220) and (0420) states have been observed in emission. Furthermore, J = 8-7, J = 9-8 lines in (031e1) were detected in emission. This finding indicates that missing low-J lines for the Δ sublevel obtained in the past is not due to the Stark effect but due to small population differences in those levels. 相似文献
4.
Normal and deuterated isotopic variants of thioborine have been produced in the gas phase by a high temperature reaction between crystalline boron and hydrogen sulfide. Millimeter- and submillimeter-wave rotational spectra have been recorded in the frequency range from 75 to 730 GHz for vibrational ground and excited states of the H10/11B32S and D10/11B32S isotopic species. The spectra of all the excited states which lie below 1500 cm−1, that are 0110, 0001, 0200, and 0220, have been observed and analyzed for each of the four isotopologues investigated. High-order Fermi resonance parameters were found important to analyze properly the spectra of the 0001 and 0200 interacting states. The improved rotational data in conjunction with earlier infrared spectroscopy results have been employed to calculate more precise anharmonic force constants and equilibrium bond lengths. 相似文献
5.
The efficient vibrational energy transfer between the first excited vibrational state of N2 and the asymmetric stretching vibrational state of OCS has allowed the observation of many pure rotational lines in different vibrational states of OCS up to 4101 cm?1: (0001), (0111), (02l1), (1001), (0002), (2110), (03l0), (04l0), and (05l0). Accurate values of some rotational, centrifugal distortion and l-doubling constants are determined. 相似文献
6.
The rotational spectra of six excited vibrational states of dimethylallene were measured and assigned to the corresponding vibrational levels, and for three more excited state spectra at least the rotational constants could be determined. Between the two lowest excited levels of symmetry species b2 and b1 of group C2v a strong a-type Coriolis coupling was found to exist. The evaluation of the resulting perturbation by a diagonalization of the energy matrix yielded ζ(a) = 0.36 and a precise value for the vibrational energy difference 48.761 GHz (1.6 cm?1). The state b2 is believed to be the first excited torsional substate (01, 10)1 of methyl internal rotation, and the rotational transitions of this state as well as those of the strongly coupled state b1 presented very irregular multiplet splittings. On the other hand, the splittings of the next-higher excited state of species a2 which could be identified as the partner torsional substate (01, 10)2, followed the regular pattern, yielding an internal rotation barrier V3 (2079 cal/mole) not unlike that derived earlier from ground state splittings. 相似文献
7.
Pradeep Risikrishna Varadwaj 《Journal of Molecular Spectroscopy》2004,227(1):23-27
Ground state (v=0) and first excited state (v=1) millimeter-wave rotational absorption spectra of cyanogen bromide (BrCN) and some of its isotopic species, have been investigated in the frequency region: 40.0-75.0 GHz using a source-modulated millimeter-wave spectrometer. Millimeter-wave radiation has been produced using a frequency multiplier, the fundamental radiation source being klystrons. BrCN has been produced by applying a dc glow discharge through a mixture of 3-bromobenzonitrile and trifluoromethylbromide (CF3Br) at low pressure. The quadrupole hyperfine structure of 81Br and 79Br have been resolved, measured, and analyzed. Finally, internuclear distances of BrCN have been determined. 相似文献
8.
Born-Oppenheimer breakdown effects and hyperfine structure in the rotational spectra of SbF and SbCl
Stephen A. Cooke 《Journal of Molecular Spectroscopy》2005,234(2):195-203
Pure rotational spectra have been measured for the ground electronic states of SbF and SbCl. The molecules were prepared by laser ablation of Sb metal in the presence of SF6 or Cl2, respectively. Their spectra were measured with a cavity pulsed jet Fourier transform microwave spectrometer. Although both molecules have two unpaired electrons, they are subject to Hund’s coupling case (c), and have X10+ ground states. The spectra have been interpreted with the formalism of 1Σ+ molecules. For both molecules spectra of several isotopomers have been measured in the ground and first excited vibrational states. Large hyperfine splittings attributable to both nuclear quadrupole coupling and nuclear spin-rotation coupling have been observed. A Dunham-type analysis has produced unusually large Born-Oppenheimer breakdown parameters, which are interpreted in terms of the electronic structures of the molecules. 相似文献
9.
Fourier transform spectra of water vapor enriched in 18O and 17O were recorded between 8012 and 9336 cm−1 and analyzed for the first time. High accuracy ab initio predictions of line positions and intensities by Partridge and Schwenke [J. Chem. Phys. 106 (1997) 4618-4639; 113 (2000) 6592-6597] were used in the process of spectrum assignment. Transitions involving the (031), (111), (130), (210), and (012) upper vibrational states were identified in the recorded spectra. As a result, 514 and 244 precise ro-vibrational energy levels were derived for the H218O and H217O molecules, respectively. High-order resonance perturbations between levels of the vibrational states involved were evidenced leading to the identification of a number of rotational levels of the (050) and (060) highly excited bending states. 相似文献
10.
《Journal of Molecular Spectroscopy》1986,116(2):499-503
The microwave spectrum of the germanium monofluoride radical in the ground electronic state has been observed by using a spectrometer with a glow discharge cell. The GeF radical was produced directly in the cell by a dc discharge in GeF4. The spectra of three isotopic species 74GeF, 72GeF, and 70GeF were analyzed to yield rotational constants, centrifugal distortion constants, Λ-doubling constants, and hyperfine interaction constants, and d. The Λ-doubling parameter p0 was found to be negative, indicating that 2Σ+ excited states make more contributions to p0 than 2Σ− excited states do. 相似文献
11.
The rotational spectrum of the unstable ClBS molecule has been investigated in the millimeter-wave region, from 80 to 195 GHz. A high-temperature reaction between crystalline boron and disulfur dichloride vapor was used to produce the molecule in a flow pyrolysis system. Eight different isotopic species were studied measuring lines in the ground and excited vibrational states 0110 (ClBS bend), 1000 (ClB stretch), 0200, 0220, and 0001 (BS stretch). The analysis of the spectra has been performed taking simultaneously into account both the Fermi resonance between the 1000 and 0200 states, and l-type resonance effects in the v2=2 vibrational state. This procedure allowed us to calculate directly deperturbed rotational constants, from which the equilibrium rotational constant of seven isotopic variants could be accurately determined yielding a much improved evaluation of the equilibrium structure of chlorothioborine: re(ClB)=1.6806±0.0001 Å and re(BS)=1.6049±0.0001 Å. The equilibrium structures of ClBS and of the related molecules HBS, FBS, HCP, FCP, and ClCP have been also theo-retically evaluated by high-level CCSD(T) calculations performed using cc-pVTZ, cc-pVQZ, and cc-pV5Z basis sets. The different trends respectively observed for the BS and CP bond lengths in the XBS and XCP triatomic molecules are discussed. 相似文献
12.
《Journal of Molecular Spectroscopy》1987,122(2):365-370
The spectra of the 2ν1 + ν3 and 3ν3 bands of 14N16O2 have been recorded by means of high-resolution Fourier transform spectroscopy and have been extensively analyzed. The (2 0 1) and (0 0 3) rotational levels deduced from the analysis have been reproduced within the experimental uncertainty using a Hamiltonian which takes into account the Coriolis interaction coupling the vibrational states of the diads {(2 2 0), (2 0 1)} and {(0 2 2), (0 0 3)}. Finally, precise sets of vibrational energies, and spin-rotation, rotational, and coupling constants have been derived for these vibrational states. 相似文献
13.
Emission spectroscopy of atmospheric pressure plasmas for bio-medical and environmental applications
Z. Machala M. Janda I. Jedlovský V. Foltin M. Morvová 《Journal of Molecular Spectroscopy》2007,243(2):194-201
The paper demonstrates several ways of use of the UV-vis optical emission spectroscopy of medium resolution for the diagnostics of atmospheric pressure air and nitrogen plasmas relevant to bio-medical and environmental applications. Plasmas generated by DC discharges (streamer corona, transient spark, and glow discharge), AC microdischarges in porous ceramics, and microwave plasma were investigated. Molecular (OH, NO, CN) and atomic (H, O, N) radicals, and other active species, e.g. N2 (C, B, A), (B), were identified. The composition of the emission spectra gives insight in the ongoing plasma chemistry. Rotational, i.e. gas, and vibrational temperatures were evaluated by fitting experimental with simulated spectra. Streamer corona, transient spark and microdischarges generate cold, strongly non-equilibrium plasmas (300-550 K), glow discharge plasma is hotter, yet non-equilibrium (1900 K), and microwave plasma is very hot and thermal (∼3000-4000 K). Electronic excitation temperature and OH radical concentration were estimated in the glow discharge assuming the chemical equilibrium and Boltzmann distribution (9800 K, 3 × 1016 cm−3). Optical emission also provided the measurement of the active plasma size of the glow discharge, and enabled calculating its electron number density (1012 cm−3). 相似文献
14.
The microwave spectra of 3-aminopropanol and three of its deuterium substituted isotopic species have been investigated in the 26.5 to 40 GHz frequency region. The rotational spectrum of only one conformer has been assigned in which presumably a hydrogen bond of the OH---N type exists. The rotational spectra of a number of excited vibrational states have been observed and assignments made for some of these excited states. The average intensity ratio for the rotational transitions between the ground and excited vibrational states indicates that the first excited state is about 120 cm?1 above the ground state.and the next higher state is roughly 200 cm?1 above the ground vibrational state. The dipole moment was determined from the Stark effect measurements to be 3.13 ± 0.04 D with its principal axes components as |μa| = 2.88 ± 0.03 D, |μb| = 1.23 ± 0.04 D and |μc| = 0.06 ± 0.01 D. The possibility of another conformer where the hydrogen bond could be of NH---O type was explored, but the spectra of such a conformer could not be identified. 相似文献
15.
New measurements of the microwave spectrum of formamide have been obtained in the frequency range from 49 to 340 GHz using the microwave spectrometer at the Institute of Radio Astronomy of NASU, Kharkov, Ukraine. An analysis of the rotational spectra of the ground, v12, v9, v11 and 2v12 excited vibrational states of the main isotopic species as well as of the ground states of the 13C, 15N and 18O substituted species has been carried out using SPFIT/SPCAT programs. The analysis of a strong Coriolis interaction coupling between v9, v11 and 2v12 vibrational states of formamide has been also fulfilled as well as the analysis of the quadrupole hyperfine structure of the observed transitions. For the first time the quadrupole coupling parameters for the excited vibrational states and for the 18O substituted species of formamide were determined. 相似文献
16.
L. Bizzocchi 《Journal of Molecular Spectroscopy》2006,235(1):117-124
The rotational spectra of 28SiF2, 29SiF2, and 30SiF2 in their ground vibrational states, as well as those of 28SiF2 in the v1 = 1, v2 = 1, v3 = 1, and v2 = 2 excited states have been studied in selected frequency regions between 80 and 700 GHz. Transitions involving a large range of quantum numbers have been observed, so that precise rotational and quartic centrifugal distortion constants could be determined for each of the spectra investigated. In addition, the complete set of sextic distortion constants was also obtained for the most abundant isotopomer in its ground vibrational state. The quadratic and cubic force constants of silicon difluoride have been refined by a least-squares procedure using a larger and more precise set of data. 相似文献
17.
The study of the vibrational state population of the O2(b1
g
+
) metastable state in a pure oxygen DC pulsed discharge is presented. The vibrational temperature is evaluated from the relative populations of v = 0, 1 and 2 states. The populations are determined from the intensities of (0-0), (1-1), (1-0) and (2-1) transitions of the atmospheric system. The most intensive (0-0) and (1-1) bands are used in the time-resolved measurements in order to determine the time evolution of the vibrational temperature during the discharge pulse. 相似文献
18.
This work gives an extensive critique of studies on methyl bromide and all its isotopic varieties with special stress on their rotational, vibrational, and rovibrational spectra. The rotational constants of more than 40 vibrational states of CH3Br and 20 of CD3Br, as well as of the ground states of all varieties, were critically examined and corrected where needed. An almost complete set of harmonic and anharmonic constants for CH3Br was derived. From the set of rotation-vibration interaction constants, new accurate equilibrium constants Ae and Be have been evaluated for CH379Br, CH381Br, CD379Br, CD381Br, from which the following equilibrium structure is obtained: re(C---H) = 1.0823 Å; re(C---Br) = 1.9340 Å; α(HCH) = 111.157°. 相似文献
19.
Zbigniew Kisiel Lech Pszczó?kowski Manfred Winnewisser Eric Herbst 《Journal of Molecular Spectroscopy》2005,233(2):231-243
We report the results of a comprehensive reinvestigation of the rotational spectrum of diethyl ether based on broadband millimetre-wave spectra recently recorded at The Ohio State University and in Warsaw, covering the frequency region 108-366 GHz. The data set for the ground vibrational state of trans-trans diethyl ether has been extended to over 2000 lines and improved spectroscopic constants have been determined. Rotational spectra in the first excited vibrational states of the three lowest vibrational modes of trans-trans-diethyl ether, ν20, ν39, and ν12 have been assigned. The v20 = 1 and v39 = 1 states are near 100 cm−1 in vibrational term value and are coupled by a strong c-axis Coriolis interaction, which gives rise to many spectacular manifestations in the rotational spectrum. All of these effects have been successfully fitted for a dataset comprising over 3000 transitions, leading to precise determination of the energy difference between these states, (ΔE/hc)=10.400222(5) cm−1. A newly developed software package for assignment and analysis of broadband spectra is described and made available. 相似文献
20.
《Journal of Molecular Spectroscopy》1986,115(1):105-116
The infrared diode laser and millimeter-wave spectra of the nitrogen chloride radical in the X3Σ− state have been observed in a DC glow discharge plasma of a N2 and Cl2 mixture, yielding spectroscopic information on 14N35Cl up to v = 4 and 14N37Cl up to v = 3. The observed infrared and millimeter-wave spectra have been simultaneously included in a least-squares analysis to determine Dunham coefficients for the vibrational and rotational energies and similar terms for the fine structure interactions. The analysis has shown that isotopic relations based on the Born-Oppenheimer approximation do not hold for the vibrational frequency, the rotational constant, and the spin-spin and spin-rotation interaction constants. It has been found that the first derivative of the spin-spin interaction constant with respect to the internuclear distance is correlated with the change in the equilibrium internuclear distance caused by the b1Σ+ ← X3Σ− excitation. 相似文献