The microwave spectrum of the chloromethyl radical, CH2Cl

1984 ◽  
Vol 62 (12) ◽  
pp. 1347-1360 ◽  
Author(s):  
Yasuki Endo ◽  
Shuji Saito ◽  
Eizi Hirota
Keyword(s):  
Gas Phase ◽  
Microwave Discharge ◽  
Rotational Spectrum ◽  
Vibronic State ◽  
Millimetre Wave ◽  
Molecular Plane ◽  
Isotopic Species ◽  
Microwave Spectrometer ◽  
Wave Region ◽  
First Time

The gas phase pure rotational spectrum of the chloromethyl radical, CH2Cl, has been observed for the first time in the millimetre wave region using a source frequency modulation microwave spectrometer equipped with a 1 m long free space absorption cell. The radical was generated by the reaction of CH3Cl with 2450-MHz microwave discharge products of CF4. The a-type R-branch transitions have been observed with resolved fine and hyperfine components for both the 35Cl and 37Cl isotopic species in the ground vibrational state. The small positive inertial defect. Δ0 = 0.0333 amu Å2, calculated from the rotational constants obtained for the 35Cl species indicates that the radical is planar in the ground vibronic state. The observed fine and hyperfine interaction constants are consistent with 2B1 symmetry, i.e., with the unpaired electron occupying a pπ orbital extending perpendicular to the molecular plane.

Spectroscopic investigations of hydrogen bonding interactions in the gas phase. II. The determination of the geometry and potential constants of the hydrogen-bonded heterodimer CH 3 CN • • • HF from its microwave rotational spectrum

1980 ◽  
Vol 370 (1741) ◽  
pp. 239-255 ◽  
Keyword(s):  
Hydrogen Bonding ◽  
Gas Phase ◽  
Spectroscopic Constants ◽  
Rotational Spectrum ◽  
Hydrogen Bonding Interactions ◽  
Isotopic Species ◽  
Microwave Rotational Spectrum ◽  
Vibration Rotation ◽  
Hydrogen Bonded

The microwave rotational spectrum of the hydrogen-bonded heterodimer CH 3 CN • • • HF has been identified and shown to be characteristic of a symmetric top. A detailed analysis of several rotational transitions for a variety of isotopic species gives the spectroscopic constants summarized in the following table: Rotational constants/MHz, vibration-rotation constants/MHz and vibrational separations/cm -1 of CH 3 CN • • • HF

Spectroscopic investigations of hydrogen bonding interactions in the gas phase. IX. Vibrational satellites in the rotational spectrum of the hydrogen-bonded homodimer HCN • • • HCN

1985 ◽  
Vol 399 (1817) ◽  
pp. 377-390 ◽  
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Hydrogen Cyanide ◽  
Spectroscopic Constants ◽  
Rotational Spectrum ◽  
Optimum Conditions ◽  
Frequency Range ◽  
Hydrogen Bonding Interactions ◽  
Microwave Spectrometer ◽  
Simulation Of Spectra

The rotational spectrum of the hydrogen cyanide dimer has been observed in the frequency range 26-40 GHz by using a Stark-modulated microwave spectrometer. Although the spectrum is very weak, even under optimum conditions, it has been possible to assign vibrational satellites in the v β progression based on the ground state and in the v β progression based on v σ ═ 1 with the aid of the computer simulation of spectra and the ground-state spectroscopic constants. The spectroscopic constants now available for the hydrogen cyanide dimerare summarized as follows: (HC 14 N) 2 (DC 14 N) 2 (HC 15 N) 2 v β ═ 1 ← 0/cm -1 35±5 30±5 35±5 v σ ═ 1 ← 0/cm -1 101 ─ ─ B o /MHz 1745.80973(50) 1661.18(26) 1684.28825(25) D J /kHz 2.133(30) (1.873) 1.900(30) r c. m ./nm 44.496 ─ 44.499 K σ /(Nm -1 ) 8.14 ─ 8.51 α β /MHz ─20.07 (2) ─17.73 (27) ─18.74 (9) γ β /MHz 0.266 (4) 0.242 (36) 0.250 (17) q β /MHz 5.33 (4) 5.44 (13) 5.15 (10) α σ /MHz (31.44) ─ ─

The Distortion Moment Microwave Spectrum of 12CH4 in the Ground Vibronic State

1975 ◽  
Vol 53 (19) ◽  
pp. 1791-1805 ◽  
Author(s):  
C. W. Holt ◽  
M. C. L. Gerry ◽  
I. Ozier
Keyword(s):  
High Resolution ◽  
Least Squares ◽  
Double Resonance ◽  
Microwave Spectrum ◽  
Experimental Techniques ◽  
Rotational Spectrum ◽  
Vibronic State ◽  
Microwave Spectrometer ◽  
The One ◽  
Theoretical Considerations

Seven Q branch transitions between 7.8 and 20 GHz have been observed in the distortion moment pure rotational spectrum of 12CH4 in its ground vibronic state. The spectrum was obtained using a conventional Stark modulated microwave spectrometer specially modified for the detection of very weak lines. From the frequencies of these seven transitions, along with the ortho–para splitting known for the (J = 2) state and two Q branch splittings measured earlier by infrared–microwave double resonance, we have determined the one quartic tensor distortion constant DT, the two sextic constants H4T and H6T, and the three octic constants L4T, L6T, and L8T. These are (in Hz): DT = (132 943.41 ± 0.71); H4T = −(16.9839 ± 0.0076); H6T = (11.0342 ± 0.0086); L4T = (20.27 ± 0.24) × 10−4; L6T = −(26.77 ± 0.35) × 10−4; L8T = −(30.0 ± 1.8) × 10−4. The errors are the standard deviations resulting from a least squares analysis. Estimates are also given of the absolute errors. These results consitute the first measurement of the octic distortion constants. The values for DT, H4T, and H6T are compared to earlier determinations. The theoretical considerations that affect the observation of these transitions are reviewed and a detailed description of the special experimental techniques used is given. The method of analysis is described. Finally, as an aid to other high resolution studies of methane and to possible astrophysical detection of the molecule, the Q branch splittings are tabulated up to J = 21.

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.

Detection of Gas-Phase Hydrogentrisulfide, HSSSH

1988 ◽  
Vol 43 (7) ◽  
pp. 617-620 ◽  
Author(s):  
D. Mauer ◽  
G. Winnewisser ◽  
Koichi M. T. Yamada ◽  
J. Hahn ◽  
K. Reinartz
Keyword(s):  
Gas Phase ◽  
Geometrical Structure ◽  
Rotational Spectrum ◽  
Hydrogen Atoms ◽  
Type Spectrum ◽  
Axis Of Symmetry ◽  
Semi Empirical ◽  
First Time ◽  
Space Cell ◽  
Rule Out

Abstract The rotational spectrum of gas phase HSSSH has been recorded for the first time in absorption with the Cologne free-space-cell millimeterwave spectrometer. In the frequency region between 80 and 300 GHz a prominent series of Q-branches has been observed and assigned. The hitherto identified rotational lines unambigously arise from a perpendicular-type spectrum. In addition, successive J lines of the compact Q-branches show no indication of the easily detectable intensity alternation which arises when the molecule possesses an axis of symmetry due to nuclear spin statistical weights. Therefore the geometrical structure of the molecule does not have a C2 axis of symmetry. The present data are not complete enough for a unique structure determination. However on the basis of the present data we can definitely rule out conformations with C2 or C2v symmetry to be responsible for the strongest observed transitions of the spectrum. The molecule is not floppy as predicted from semi empirical MO calculations. On the contrary the conformation observed is rather rigidly locked into one position with no sign of possible internal rotation. We consider a sulfur triangle with the two hydrogen atoms sticking out symmetrically to the same side of the SSS-plane to be the most likely structure.

Ground state molecular parameters of phosphine, PH3, from the simultaneous analysis of the high-resolution infrared, microwave and submillimeterwave spectra

1985 ◽  
Vol 50 (11) ◽  
pp. 2480-2492 ◽  
Author(s):  
Soňa Přádná ◽  
Dušan Papoušek ◽  
Jyrki Kauppinen ◽  
Sergei P. Belov ◽  
Andrei F. Krupnov ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Ground State ◽  
Unitary Transformation ◽  
Point Of View ◽  
Acoustic Detection ◽  
Molecular Parameters ◽  
Microwave Spectrometer ◽  
Fourier Transform Spectra ◽  
First Time

Fourier transform spectra of the ν2 band of PH3 have been remeasured with 0.0045 cm-1 resolution. Ground state combination differences from these data have been fitted simultaneously with the microwave and submillimeterwave data to determine the ground state spectroscopical parameters of PH3 including the parameters of the Δk = ± 3n interactions. The correlation between the latter parameters has been discussed from the point of view of the existence of two equivalent effective rotational operators which are related by a unitary transformation. The ΔJ = 0, +1, ΔK = 0 (A1 ↔ A2, E ↔ E) rotational transitions in the ν2 and ν4 states have been measured for the first time by using a microwave spectrometer and a radiofrequency spectrometer with acoustic detection.

scholarly journals Frequency-diverse multimode millimetre-wave constant-ϵr lens-loaded cavity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. A. B. Abbasi ◽  
V. F. Fusco ◽  
O. Yurduseven ◽  
T. Fromenteze
Keyword(s):  
Signal To Noise Ratio ◽  
Cost Effective ◽  
Doa Estimation ◽  
Frequency Diversity ◽  
Millimetre Wave ◽  
Single Lens ◽  
Dielectric Lens ◽  
Diversity Principle ◽  
First Time ◽  
Multi Mode

AbstractThis paper presents a physical frequency-diverse multimode lens-loaded cavity, designed and used for the purpose of the direction of arrival (DoA) estimation in millimetre-wave frequency bands for 5G and beyond. The multi-mode mechanism is realized using an electrically-large cavity, generating spatio-temporally incoherent radiation masks leveraging the frequency-diversity principle. It has been shown for the first time that by placing a spherical constant dielectric lens (constant-ϵr) in front of the radiating aperture of the cavity, the spatial incoherence of the radiation modes can be enhanced. The lens-loaded cavity requires only a single lens and output port, making the hardware development much simpler and cost-effective compared to conventional DoA estimators where multiple antennas and receivers are classically required. Using the lens-loaded architecture, an increase of up to 6 dB is achieved in the peak gain of the synthesized quasi-random sampling bases from the frequency-diverse cavity. Despite the fact that the practical frequency-diverse cavity uses a limited subset of quasi-orthogonal modes below the upper bound limit of the number of theoretical modes, it is shown that the proposed lens-loaded cavity is capable of accurate DoA estimation. This is achieved thanks to the sufficient orthogonality of the leveraged modes and to the presence of the spherical constant-ϵr lens which increases the signal-to-noise ratio (SNR) of the received signal. Experimental results are shown to verify the proposed approach.

CsOH and its Lighter Homologues – a Comparison

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1229-1236
Author(s):  
Matthias Wörsching ◽  
Constantin Hoch
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Structure Type ◽  
Alkali Metal Hydroxide ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Cesium Hydroxide ◽  
Free Ion ◽  
The One ◽  
First Time

Abstract Cesium hydroxide, CsOH, was for the first time characterised on the basis of single-crystal data. The structure is isotypic to the one of the room-temperature modification of NaOH and can be derived from the NaCl structure type thus allowing the comparison of all alkali metal hydroxide structures. Raman spectroscopic investigations show the hydroxide anion to behave almost as a free ion as in the gas phase. The X-ray investigations indicate possible H atom positions.

The microwave spectrum of the ClS2 free radical

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1043-1050 ◽  
Author(s):  
Masaharu Fujitake ◽  
Eizi Hirota
Keyword(s):  
Free Radical ◽  
Force Field ◽  
Electronic Spectroscopy ◽  
Spin Rotation ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Harmonic Force ◽  
Isotopic Species ◽  
Spin Resonance ◽  
Centrifugal Distortion Constants

The rotational spectrum of the ClS2 free radical in the gaseous phase has been observed in the millimetre- and submillimetre-wave regions. The ClS2 radical was generated by a dc glow discharge in either S2Cl2 or SCl2. Both a- and b-type R-branch transitions, most of which were split into two fine structure components, were detected for both of the 35Cl and 37Cl isotopic species in the ground vibronic state. As expected from the small hyperfine interaction constants reported by an electron spin resonance (ESR) study, the hyperfine structure was resolved for none of the transitions observed in the present study. Analysis of the observed transition frequencies yielded rotational and centrifugal distortion constants and also spin–rotation interaction constants with their centrifugal corrections. The spin–rotation interaction constants obtained in the present study were consistent with g values of the ESR study. The rotational constants of the two isotopic species led to the structure parameters r(S—S) = 1.906 (7) Å, r(S—Cl) = 2.071 (5) Å, and θ(SSCl) = 110.3 (4)°. A harmonic force field was derived from the observed centrifugal distortion constants and inertial defects combined with the ν1 frequency reported in literature on electronic spectroscopy. This harmonic force field yielded the ν2 and ν3 frequencies (445 (21) and 213.0 (2) cm−1, respectively, for 35ClS2), which differed considerably from the values reported previously.

Analysis of chlorinated hydrocarbons in gas phase using a portable membrane inlet mass spectrometer

2016 ◽  
Vol 8 (36) ◽  
pp. 6607-6615 ◽  
Author(s):  
Stamatios Giannoukos ◽  
Boris Brkić ◽  
Stephen Taylor
Keyword(s):  
Gas Phase ◽  
Mass Spectrometer ◽  
Gaseous Phase ◽  
Chlorinated Hydrocarbons ◽  
Volatile Chlorinated Hydrocarbons ◽  
First Time

A compact portable membrane inlet mass spectrometer (MIMS) has been used for the first time to detect and monitor, both qualitatively and quantitatively, volatile chlorinated hydrocarbons in the gaseous phase.

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