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The microwave spectrum of divinyl ether has been observed and a, b, and c type rotational transitions of one conformer assigned. This conformer has rotational constants closely related to the cis-trans planar form. The inertial defect and dipole moment reveal that it is not planar. This nonplanarity almost certainly results because of strong repulsion between the β hydrogen of the cis vinyl group and the α hydrogen of the trans vinyl group. The c type transitions are split 53 MHz by inversion tunneling. The dipole moment has been obtained from Stark effect measurements and is 0.782 debye. 相似文献
13.
J. Pfab J. Hager W. Krieger C. V. Boughton R. E. Miller H. Zacharias M. M. T. Loy P. A. Roland A. Sudbo B. E. Lehmann C. H. Chen G. S. Hurst M. G. Payne R. D. Willis S. D. Kramer E. E. Marinero C. T. Rettner R. N. Zare H. Rottke K. H. Welge C. C. Wang M. T. Myers D. Zhou J. W. Hudgens T. G. DiGiuseppe M. C. Lin E. Riedle H. J. Neusser E. W. Schlag J. Pfeifler P. G. Carrick R. F. Curl Jr. F. K. Tittel C. G. Atkins G. Hancock R. F. Menefee R. R. Hall M. J. Berry D. M. Burland 《Applied physics. B, Lasers and optics》1982,28(2-3):112-123
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.
A microwave-optical double resonance (MODR) involving the and components of the 100, 10 ← 91, 9 rotational transition of the ground vibronic state of 14N16O2 has been observed using the 4579 Å Ar+ laser line for excitation. By means of high resolution study of the laser excited fluorescence, the optical transition has been assigned to the spin component of the 90, 9 ← 100, 10 transition from the ground vibronic state to an unknown vibrational state of A1 symmetry of the 2B2 electronic state. 相似文献
16.
Chen HB Thweatt WD Wang J Glass GP Curl RF 《The journal of physical chemistry. A》2005,109(10):2207-2216
The branching of the title reaction into several product channels has been investigated quantitatively by laser infrared kinetic spectroscopy for CH(4) and CD(4). It is found that OH (OD) is produced in 67 +/- 5% (60 +/- 5%) yield compared to the initial O((1)D) concentration. H (D) product is produced in 30 +/- 10%(35 +/- 10%). H(2)CO is produced in 5% yield in the CH(4) system (it was not possible to measure the CD(2)O yield in the CD(4) case). D(2)O is produced in 8% yield in the CD(4) system (it was not feasible to measure the H(2)O yield). The ratio of the overall rate constant of the CD(4) reaction to the overall rate constant of the O((1)D) + N(2)O reaction was determined to be 1.2(5) +/- 0.1. A measurement of the reaction of O((1)D) with NO(2) gave 1.3 x 10(-10) cm(3) molecule(-1) s(-1) relative to the literature values for the rate constants of O((1)D) with H(2) and CH(4). Hot atom effects in O((1)D) reactions were observed. 相似文献
17.
Recently Irle, Morokuma, and collaborators have carried out a series of quantum chemical molecular dynamics simulations of carbon clustering. The results of these computer experiments are that carbon clusters of size greater than 60 atoms are rapidly formed, anneal to giant fullerenes, and then these fullerenes shrink. The simulation could not be carried to long enough times for the shrinking to reach C60, but they propose reasonably that this shrinking process ultimately forms buckminsterfullerene. However, these simulations do not reveal the force driving the shrinking process. Here, this driving force for shrinking is found to be reactions in which C2 is swapped between fullerenes. The key element is that for typical fullerenes the equilibrium constants for such C2 interchanges are near unity, resulting in expansion of the breadth of the fullerene distribution in an annealing process. When fullerenes of 60 or 70 atoms are populated by shrinking, they fall into the local energy minimum of buckminsterfullerene or D5h C70. This simple mechanism accounts for the high yields (>20%) of buckminsterfullerene that can be achieved in pure carbon systems. 相似文献
18.
The microwave spectrum of chloromethyl methyl ether has been studied in the region 12.4–40 GHz. For 35Cl species, a- and c-type transitions have been assigned for the ground state, the first excited state of the chloromethyl torsional mode, and the first excited state of the methyl torsional mode. Assignments were also made for the ground state of 37Cl species. The assigned transitions are due to the gauche conformer. The nuclear quadrupole coupling constants were determined for the ground state of 35Cl and 37Cl species. The observed A-E splittings of the rotational transitions arising from the three vibrational states indicate a strong coupling between the two torsional vibrations. A model calculation based on the Hamiltonian previously used by Butcher and Wilson (J. Chem. Phys.40, 1671 (1964)), was carried out to account for the splittings and the vibrational frequencies of the two torsional modes. The barrier to internal rotation of the methyl group is estimated to be V3 = 647 ± 17 cm?1 (1.84 ± 0.05 kcal/mole). 相似文献
19.
L. Menzel A.A. Kosterev R.F. Curl F.K. Tittel C. Gmachl F. Capasso D.L. Sivco J.N. Baillargeon A.L. Hutchinson A.Y. Cho W. Urban 《Applied physics. B, Lasers and optics》2001,72(7):859-863
Two configurations of a continuous wave quantum cascade distributed feedback laser-based gas sensor for the detection of NO
at a parts per billion (ppb) concentration level, typical of biomedical applications, have been investigated. The laser was
operated at liquid nitrogen temperature near λ=5.2 μm. In the first configuration, a 100 m optical path length multi-pass
cell was employed to enhance the NO absorption. In the second configuration, a technique based on cavity-enhanced spectroscopy
(CES) was utilized, with an effective path length of 670 m. Both sensors enabled simultaneous analysis of NO and CO2 concentrations in exhaled air. The minimum detectable NO concentration was found to be 3 ppb with a multi-pass cell and 16 ppb
when using CES. The two techniques are compared, and potential future developments are discussed.
Received: 1 November 2000 / Revised version: 19 January 2001 / Published online: 20 April 2001 相似文献
20.
A. Kosterev G. Wysocki Y. Bakhirkin S. So R. Lewicki M. Fraser F. Tittel R.F. Curl 《Applied physics. B, Lasers and optics》2008,90(2):165-176
Quantum cascade (QC) lasers are virtually ideal mid-infrared sources for trace gas monitoring. They can be fabricated to operate
at any of a very wide range of wavelengths from ∼ 3 μm to ∼ 24 μm. Seizing the opportunity presented by mid-infrared QC lasers,
several groups world-wide are actively applying them to trace gas sensing. Real world applications include environmental monitoring,
industrial process control and biomedical diagnostics. In our laboratory we have explored the use of several methods for carrying
out absorption spectroscopy with these sources, which include multipass absorption spectroscopy, cavity ring down spectroscopy
(CRDS), integrated cavity output spectroscopy (ICOS), and quartz-enhanced photoacoustic spectroscopy (QEPAS).
PACS 42.62.Fi; 42.62.Be; 07.88.+y; 33.20.Ea 相似文献