Millimetre-wave laboratory detection of H2COH+

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1078-1081 ◽  
Author(s):  
D. Chomiak ◽  
A. Taleb-Bendiab ◽  
S. Civis ◽  
T. Amano
Keyword(s):  
Ground State ◽  
Molecular Clouds ◽  
Rotational Transition ◽  
Infrared Detection ◽  
Rotational Spectrum ◽  
Molecular Constants ◽  
Negative Glow ◽  
Millimetre Wave ◽  
Magnetically Confined ◽  
Interstellar Molecular Clouds

The ground-state rotational spectrum of protonated formaldehyde, H2COH+, has been identified and assigned following the infrared detection by Amano and Warner using a magnetically confined extended negative glow discharge as a production source. The molecular constants have been determined more accurately. These parameters provide the pure rotational transition frequencies that are accurate enough for radio astronomical searches for this ion in interstellar molecular clouds.

Sub-Doppler Saturation Spectroscopy of HCN up to 1 THz and Detection of J = 3 —> 2 (4—> 3) Emission from TMC1

2002 ◽  
Vol 57 (8) ◽  
pp. 669-681 ◽  
Author(s):  
Volker Ahrens ◽  
Frank Lewen ◽  
Shuro Takano ◽  
Gisbert Winnewisser ◽  
Štepán Urban ◽  
...  
Keyword(s):  
Ground State ◽  
Rotational Transition ◽  
Chem Phys ◽  
Swiss Alps ◽  
Center Frequency ◽  
Rotational Spectrum ◽  
Molecular Constants ◽  
Emission Data ◽  
Selection Rules ◽  
Rotational Transitions

Very high-resolution ( ∼ 30 kHz) and very precise (±2 kHz) saturation dip and crossover dip measurements are reported for HCN. Nine consecutive rotational transitions of the vibrational ground state were recorded, covering the rotational spectrum up to the J = 11 ← 10 transition at 975 GHz. Commencing the saturation dip measurements with the J = 3 ← 2 transition located at 265 886.4 MHz, all rotational transitions were measured up to J = 11 ← 10 (ΔF = 1), positioned at a center frequency of 974 487.2 MHz. It has become possible to resolve the hyperfine structure of every rotational transition to varying degrees. Transitions obeying the selection rules ΔJ = 1, ΔF = 0 are have been resolved, those obeying the selection rules J = 1, F = 1 are only resolved for transitions lower than the J = 6 ← 5 transition.These new experimental saturation dip data, together with the molecular beam maser emission data of the J = 1 → 0 and J = 2 → 1 transitions reported by De Lucia and Gordy, (Phys. Rev. 187, 58 (1969)), and the recent terahertz measurements performed in this laboratory up to J = 22-21 at 1.946 THz (Maiwald et al., J. Mol. Spectrosc. 202, 166 (2000)), were subjected to a least squares analysis which yielded a highly precise set of molecular constants for the ground state of HCN: B = 44 315.974 970 (156) MHz, D = 0.087 216 35 (169) MHz, H = 0.086 96 (242) Hz; eQq = -4.709 03 (162) MHz, eQqJ = 0.244 (88) Hz, CN = 10.09 (38) kHz, CNJ = -0.0143 (86) mHz. Two constants, the hydrogen spin-rotation, CH = -4.35 (5) kHz, and the spin-spin interaction between the proton and nitrogen nucleus, SNH = 0.154 (3) kHz, can not be determined from the saturation dip measurements and have been taken from Ebenstein and Muenter, J. Chem. Phys. 80, 3989 (1984). There also a value for the ground state permanent electric dipole moment (in Debye’s) is given, which we quote for completeness: 〈μ〉000 = 2.985 188 (3) D. We also report the discovery of the J = 3 → 2 and J = 4 → 3 ground state rotational transitions of HCN in the dark, cold molecular cloud TMC1 by using the KOSMA 3m-Submillimeter Telescope located in the central Swiss Alps. For the J = 3 → 2 transition the hyperfine splitting has partly been resolved. The intensities of the hyperfine components are anomalous, and they are not in thermodynamic equilibrium.

Analysis of Torsion in a Three-Top Molecule. Torsional Barrier and Moment of Inertia of Trimethyl Ethynyl Germane

1996 ◽  
Vol 51 (4) ◽  
pp. 299-305 ◽  
Author(s):  
K. Voges ◽  
J. Gripp ◽  
H. Hartwig ◽  
H. Dreizler
Keyword(s):  
Internal Rotation ◽  
Ground State ◽  
Molecular Beam ◽  
Rotational Constant ◽  
Rotational Transition ◽  
Microwave Spectroscopy ◽  
Rotational Spectrum ◽  
Molecular Symmetry ◽  
Torsional Barrier ◽  
Symmetry Species

Internal rotation effects for a large number of molecules containing one or two symmetric internal rotors have been investigated using microwave spectroscopy. The high resolution of molecular beam Fourier transform microwave spectroscopy revealed now the internal rotation fine structure in the rotational spectrum of trimethyl ethynyl germane, (CH3)3GeC=CH. After assigning the rotational transition J = 1 → 0 in the vibrational and torsional ground state to the symmetry species of the molecular symmetry group G162 , the torsional barrier V3 and the rotational constant B0 could be determined to (4.5±0.2) kJ/mol and (1823.370±0.010) MHz, respectively.

Rotational Spectrum of 2,3-Benzofuran

2003 ◽  
Vol 68 (9) ◽  
pp. 1572-1578 ◽  
Author(s):  
B. Michela Giuliano ◽  
Walther Caminati
Keyword(s):  
Excited State ◽  
Ground State ◽  
Rotational Spectrum ◽  
Frequency Range ◽  
Supersonic Expansion ◽  
Rotational Constants ◽  
Millimetre Wave ◽  
Rotational Spectra ◽  
Wave Absorption ◽  
Free Jet

The rotational spectra of the ground state and of one vibrational satellite of 2,3-benzofuran have been measured by millimetre-wave absorption free jet spectroscopy in the frequency range 60-78 GHz. The value of the inertial defect (-0.072 uÅ2) shows the molecule to be planar. The shifts of the rotational constants in going from the ground to the excited state indicate that the observed vibrational satellite does not belong to the two lowest energy motions, the butterfly and 1,3-ring-twisting, which undergo relaxation upon the supersonic expansion.

scholarly journals The Submillimeter Wave Astronomy Satellite

1990 ◽  
Vol 123 ◽  
pp. 251-251 ◽  
Author(s):  
G.J. Melnick
Keyword(s):  
Fine Structure ◽  
Chemical Composition ◽  
Ground State ◽  
Molecular Clouds ◽  
Large Scale ◽  
Rotational Transition ◽  
Submillimeter Wave ◽  
Important Species ◽  
Structure Transition ◽  
Large Scale Survey

AbstractThe Submillimeter Wave Astronomy Satellite (SWAS) is a NASA Small-Explorer Class experiment whose objective is to study both the chemical composition and the thermal balance in dense (NH2 > 103 cm−3) molecular clouds and, by observing many clouds throughout our galaxy, relate these conditions to the processes of star formation. To conduct this study SWAS will be capable of carrying out both pointed and scanning observations simultaneously in the lines of four important species: (1) the H2O (110–101) 556.963 GHz ground-state ortho transition, (2) the O2 (3,3–1,2) 487.249 GHz transition, (3) the CI (3P1 – 3P0) 492.162 GHz ground-state fine structure transition, and (4) the 13CO (J = 5–4) 550.926 GHz rotational transition. These atoms and molecules are predicted to be among the most abundant within molecular clouds and, because they possess low-lying transitions with energy differences (ΔE/k) between 15 and 30K (temperatures typical of many molecular clouds), these species are believed to be dominant coolants of the gas as it collapses to form stars and planets. A large-scale survey in these lines is virtually impossible from any platform within the atmosphere due to telluric absorption.

Centrifugal Distortion Parameters of Fulminic Acid, HCNO, from the Millimeter-Wave Rotational Spectra

1971 ◽  
Vol 26 (1) ◽  
pp. 128-131 ◽  
Author(s):  
Manfred Winnewisser ◽  
Brenda P. Winnewisser
Keyword(s):  
Millimeter Wave ◽  
Ground State ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Vibrational States ◽  
Molecular Constants ◽  
Rotational Spectra ◽  
First Excited State ◽  
Bending Modes ◽  
Distortion Parameters

Abstract A newly designed millimeter-wave spectrometer has been employed for precise measurements of the millimeter-wave rotational spectrum of HCNO. Absorptions in several excited vibrational states as well as the ground state could be measured. The present paper presents the observed frequen­ cies and molecular constants obtained for the ground state and the first excited state of v4 and of v5, the vibrational bending modes

scholarly journals The rotational a-type spectrum of [13C]diazirine, H2CN2

1984 ◽  
Vol 62 (12) ◽  
pp. 1217-1225 ◽  
Author(s):  
Klaus Möller ◽  
Jürgen Vogt ◽  
Manfred Winnewisser ◽  
JØrn Johs. Christiansen
Keyword(s):  
Hyperfine Structure ◽  
Rotational Transition ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Rotational Constants ◽  
Millimetre Wave ◽  
Quadrupole Coupling ◽  
Type Spectrum ◽  
Wave Region ◽  
Centrifugal Distortion Constants

The rotational spectrum of 13C isotopically enriched diazirine, H213C14N2, has been recorded in the region between 12 and 250 GHz. From an analysis of the nuclear hyperfine structure of the rotational transitions, quadrupole coupling and spin-rotational constants have been determined. Using Watson's A-reduced Hamiltonian, the rotational constants, the quartic and some sextic centrifugal distortion constants have been obtained for the ground vibrational state. The rotational constants obtained are[Formula: see text]The nuclear quadrupole coupling constants and the spin-rotation constants are[Formula: see text]for the two identical quadrupolc nitrogen nuclei. The accuracy of the constants obtained allows us to evaluate the line positions and hyperfine structure of any rotational transition in the microwave and millimetre wave region.

Molecular Constants of the Ground State of the I2 Molecule

1951 ◽  
Vol 19 (9) ◽  
pp. 1210-1211 ◽  
Author(s):  
D. H. Rank ◽  
William. M. Baldwin
Keyword(s):  
Ground State ◽  
Molecular Constants

Refined molecular constants for the states of H2

1985 ◽  
Vol 63 (11) ◽  
pp. 1416-1417 ◽  
Author(s):  
Michel Larzillière ◽  
Françoise Launay ◽  
Jean-Yves Roncin
Keyword(s):  
Ground State ◽  
Molecular Constants

Refined molecular constants for the states C, D, D′, and D″ [Formula: see text] of H2 have been obtained using the best values of the ground-state constants derived recently by Dabrowski. A few high J values of C and D states are reassigned.

Rotational Analysis of the lΠ–XlΣ+ System of C80Se

1974 ◽  
Vol 52 (9) ◽  
pp. 813-820 ◽  
Author(s):  
René Stringat ◽  
Jean-Paul Bacci ◽  
Marie-Hélène Pischedda
Keyword(s):  
Emission Spectrum ◽  
Ground State ◽  
High Frequency ◽  
Rotational Analysis ◽  
Molecular Constants ◽  
High Frequency Discharge ◽  
Perturbed State ◽  
Simple Evaluation ◽  
Π State

The strongly perturbed 1Π–X1Σ+ system of C80Se has been observed in the emission spectrum of a high frequency discharge through selenium and carbon traces in a neon atmosphere. The analysis of five bands yields, for the molecular constants of the ground state, the values Be″ = 0.5750 cm−1, [Formula: see text], αe″ = 0.00379 cm−1, re″ = 1.676 Å, ΔG″(1/2) = 1025.64 cm−1, and ΔG″(3/2) = 1015.92 cm−1. The numerous perturbations in the 1Π state prohibit the simple evaluation of the constants of the perturbed state and of the perturbing ones.

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