Laboratory millimeter and submillimeter spectrum of HOC^+

The J = 1→2, 2→3, and 3→4 rotational transitions of the molecular ion HOC^+ have been measured in the laboratory at frequencies from 178 to 358 GHz. The data should permit astronomers to confirm the recent possible sighting of the J = 1→0 transition of HOC^+ in Sgr B2 at 89.5 GHz

Millimeter and Submillimeter Spectroscopy of Molecules of Atmospheric Importance

In our proposal we laid out work in three areas of relevance to atmospheric science: millimeter and submillimeter spectroscopy, variable temperature pressure broadening, and band and intensity measurements in the FIR. Below we will briefly discuss our progress during the second year of this project. In our millimeter and submillimeter (mm/submm) spectroscopic work, one of our goals has been to work towards the unification of the rotational (primarily obtained by mm/submm techniques) and rotational-vibrational (primarily obtained by infrared techniques) data sets in the context of theoretically well founded models which take advantage of the strengths of the data from each experimental technique. From the point of view of the development of the optimal data base for atmospheric observations, this is clearly a desirable goal. During the first year of this project we did an analysis of a weighted, mixed infrared and mm/submm data set of the n = 0, 1, and 2 torsional states of the ground vibrational state of HOOH. The purpose of this work is to provide a unified understanding of the spectrum, which is applicable in both the rotational and rotational - vibrational regimes. We have succeed in doing this in the context of a single weighted fit which accounts for both data sets to their respective experimental uncertainty (-0.1 and 10 MHz, respectively). Additionally, we have now done a similar analysis on the n = 0 torsional state of v(sub 3) and begun a similar analysis on v(sub 6). For several years we have been working on the mm/submm rotational spectra of the many excited vibrational states of HNO3, again with particular emphasis on the relationships between the mm/submm and infrared spectra. During the first year of this project we were able to use mm/submm spectroscopy to fully resolve the torsional splittings in 2 v(sub 9) and v(sub 5), establish a theoretically well founded quantitative relation between them, and show that both have their physical origin in the torsional motion of the v(sub 9) mode.This result has now been incorporated in a recent reanalysis of the infrared spectrum and has resulted in improved fits - eliminating what was in retrospect a systematic error associated with this previously unknown effect

A Fast Scan Submillimeter Spectroscopic Technique

A new fast scan submillimeter spectroscopic technique (FASSST) has been developed which uses a voltage tunable backward wave oscillator (BWO) as a primary source of radiation, but which uses fast scan (~105 Doppler limited resolution elements/s) and optical calibration methods rather than the more traditional phase or frequency lock techniques. Among its attributes are (1) absolute frequency calibration to ~1/10 of a Doppler limited gaseous absorption linewidth (\u3c0.1 MHz, 0.000 003 cm-1), (2) high sensitivity, and (3) the ability to measure many thousands of lines/s. Key elements which make this system possible include the excellent short term spectral purity of the broadly (~100 GHz) tunable BWO; a very low noise, rapidly scannable high voltage power supply; fast data acquisition; and software capable of automated calibration and spectral line measurement. In addition to the unique spectroscopic power of the FASSST system, its implementation is simple enough that it has the prospect of impacting a wide range of scientific problems

Diversification et innovation industrielles au Grand-Duche de Luxembourg

Cahiers economiques de la Banque Internationale, no 2/83Bibliotheque Nationale, Luxembourg (Grand Duche) / BN - Bibliothèque NationaleSIGLELULuxembur

MILLIMETER AND SUBMILLIMETER SPECTRUM OF DSSD.

Work at Duke University supported by the U.S. Air Force Office of Scientific Research. $^{1}$ G. Winnewisser, M. Winnewisser and W. Gordy, J. Chem. Phys. 49, 3465 (1968). $^{2}$ G. Winnewisser and P. Helminger, Bull. Am. Phys. Soc. II, Vol. 14, No. 4, 622 (1969).Author Institution: Department of Physics, Duke University; Division of Pure Physics, National Research Council of CanadaThe millimeter and submillimeter wave spectra of DSSD have been measured using a 6 ft free space cell. DSSD is a very slightly asymmetric top molecule ($K = -0.999992$) and its spectrum shows all the features of a $\bot$-type $transition.^{1}$ The outstanding features of this type of rotational spectrum are the strong Q-branch absorption lines. From the assigned millimeter and submillimeter ground state Q-branch transitions of the $D^{32}S^{32}SD$ species, the band centers for the $^{R}Q_{0}, ^{R}Q_{1}$ and $^{R}Q_{2}$ branches are determined to be: $\begin{array}{l} ^{R}Q_{0}: 69 916.42\pm0.3 Mc/sec (2.332 cm^{-1})\\ ^{R}Q_{1}: 209 737.0 \pm 2.0 Mc/sec (6.996 cm^{-1})\\ ^{R}Q_{2}: 349 540.0 \pm 3.0 Mc/sec (11.659 cm^{-1}) \end{array}$ All transitions originating from the $K \neq 0$ levels show the expected K-type splitting. Because of this and the fact that there is only a small difference between the rotational constants (C-B = -0.29 Mc/sec) the Q-branches have a rather complex structure. A simultaneous analysis of the Q-branch positions shows that the centrifugal distortion treatment with correction terms to $P^{6}$ is not quite sufficient to account for the observed spectra. A similar result was obtained for $HSSH.^{2}$ For the $^{R}Q_{0}$ and $^{R}Q_{1}$branches the measurements were extended to the first excited states (torsional vibrational state $v_{t} = 1$ and the S-S bond stretching vibrational state $v_{o} = 1$). The internal rotational splitting of the ground state as well as the excited states is too small to be resolved, which is in agreement with our observations on HSSH

AN ANALYSIS OF THE ROTATIONAL SPECTRUM AND ENERGY LEVELS OF HYDROGEN SELENIDE

$^{1}$ R A. Hill, thesis, Michigan State University, 1963. This work was supported by the National Science Foundation, Grant GP-34590. Present address of Paul Helminger: University of South Alabama Mobile, Alabama, 36688.""Author Institution: Department of Physics, Duke University,Ninety-four previously unobserved transitions of the five isotopic species of hydrogen selenide have been measured in the 100-600 GHz region of the microwave spectrum. Watson’s reduced centrifugal distortion Hamiltonian has been used to analyze this data in conjunction with the infrared combination differences of $Hill.^{1}$ The energy levels and spectral constants which result are in good agreement with both the infrared and microwave data. The less abundant $^{76}Se$, $^{77}Se$, and $^{82}Se$ species, for which no infrared combination differences are available, were analyzed primarily on the basis of the observed microwave transitions. Isotopic comparisons have been made and the effects of the symmetry (K $\approx$ 0.82) on the centrifugal distortion analysis considered. For $H_{2}$$^{80}Se$ the rotational and $P^{4}$ distortion constants are (in MHZ): A = 244 099.89, B = 232 561.95, C = 116 874.93, $\Delta_{j} = 34.950, \Delta_{JK} = -118.119, \Delta K$ = 88.1173, $\delta_{j} = -2.12091, \delta_{K} - 461.0394$

MILLIMETER AND SUBMILLIMETER SPECTROSCOPY OF CHLORINE NITRATE: THE Cl QUADRUPOLE TENSOR AND THE HARMONIC FORCE FIELD

Author Institution: Jet Propulsion Laboratory, California Institute of Technology; Department of Physics, University of South Alabama; Department of Chemistry, University of South AlabamaThe rotational spectrum of $CIONO_{2}$ has been (re-) investigated in the millimeter and submillimeter regions in the ground vibrational and first excited torsional states for both $^{35}$Cl and $^{37}$Cl isotopomers. A large number of $a$- and $b$-type $R$- and $Q$-branch as well as $b$-type $P$-branch transitions have been observed. This has enabled the improvement of the spectroscopic constants and the prediction of lines in the submillimeter region. Accidental near-degeneracies of rotational levels allowed the observation of a $\Delta J = 2$ transition and the precise determination of the off-diagonal quadrupole coupling constant $\chi_{ab}$. The quartic distortion constants along with the vibrational wavenumbers and inertial defects have been used to calculate a harmonic force field. The results will be related to the molecular structure determined from an electron diffraction study and to data from related molecules such as $Cl_{2}O$

ENERGY TRANSFER MECHANISMS IN OPTICALLY PUMPED 13CH3F∗^{13}CH_{3}F^{*}

$^{*}$ Supported by the Army Research Office, Grant DAAG-29-80-C-0026Author Institution:Energy transfer mechanisms in the $^{13}CH_{3}F$ 1.2 mm optically pumped far-infrared laser have been studied with the aid of a millimeter wave spectrometer. In this laser the 9P32 line of a $CO_{2}$ laser optically pumps $^{13}CH_{3}F$ from the J=4, K=3 ground vibrational state to the J=5, K=3, $V_{3}$ = 1 vibrational state. Absorption/Emission coefficients are observed for $^{13}CH_{3}F$ both with and without optical pumping. Population inversions between the following states have been observed; J=5, K=3 and J=4, K=3 both in the ground and $V_{3}$=1 vibrational states and J=4, K=3 and J=3, K=3, $V_{3}$=1 vibrational states. A corresponding enhanced absorption for J=3$\rightarrow 4$, K=3 ground state has been noted. Pumping also enhances absorptions for J=4$\rightarrow$5, $K\not=$3, $V_{3}$=1 and J=3$\rightarrow$ K $\not=$3, $V_{3}$=1 transitions. From these data rotational and vibrational relaxation times are calculated

MILLIMETER AND SUBMILLIMETER SPECTRA OF THE DEUTERO AMMONIAS

Author Institution: Department of Physics, Duke UniversityThe microwave spectra of the duetero ammonias $NH_{2}D$ and $ND_{2}H$ have been investigated by means of a millimeter and submillimeter wave spectrometer which we have described previously at this meeting. The spectra of these light asymmetric rotors consists of doublets which result from a splitting of the rotational energy levels by the molecular inversion. Watson’s formulation of the rotation-distortion Hamiltonian has been used to analyze the rotational spectrum of these molecules. An accurate analysis of the inversion splittings, which are strongly dependent upon the rotational energy state, has been used to confirm the assignment of the rotation-inversion transitions