Far-infrared Laser Magnetic Resonance Spectrum Research Articles

The far-infrared laser magnetic resonance spectrum of vibrationally excited C 2H

Some previously observed but unassigned lines in the laser magnetic resonance spectrum of the F + CH 4 flame at 490.4 μm have been assigned to the N = 7 ← 6, + ← − transition of the C 2H radical in its (010) vibrational level. The spectrum is an interesting example of a magnetic resonance spectrum of a radical displaying Hund's case (b) coupling and arises because the laser frequency is very close to the zero-field molecular frequency. The measured resonances are combined with recently available millimeter-wave observations of C 2H in the same vibrational level to give an improved set of molecular parameters. Some of these parameters provide quantitative information on the extent of the mixing of the X ̃ 2 Σ + state with the low-lying A ̃ 2 Π state of C 2H.

The microwave spectrum of the PH 2 radical

Five more rotational transitions of the PH 2 radical in the ground state were observed in the submillimeter-wave region. Sixty-one fine and hyperfine components were measured for the five transitions. An analysis of the observed spectra, combined with the microwave spectra reported in the previous paper, far-infrared and mid-infrared laser magnetic resonance spectra, and laser-induced fluorescence spectra obtained by other workers, improved the accuracy of most of the molecular constants given in the previous paper.

The far-infrared Laser Magnetic Resonance spectrum of the 17OH radical: Determination of nuclear hyperfine parameters

The far-infrared (FIR) Laser Magnetic Resonance (LMR) spectrum of the 17OH radical in the v = 0 level of the X 2Π state has been studied in detail. The measurements have been analyzed and, in combination with some earlier EPR measurements, subjected to a single least-squares fit using an effective Hamiltonian. A full set of 17O nuclear hyperfine parameters has been determined. Some implications of these parameter values for the electronic wavefunction of OH are considered.

The far-infrared laser magnetic resonance spectrum of the CF radical and determination of ground state parameters

Observations in the far-infrared laser magnetic resonance spectrum of the CF radical in its ground 2Π state have been extended to include fine structure transitions between the two spin components. The data are fitted together with all previous measurements relating to the v = 0 level to obtain a complete set of molecular parameters, including the spin-orbit splitting which has been determined at 77.196916(14) cm −1. The implications for the electronic structure of various parameters are also discussed.

The far-infrared laser magnetic resonance spectra of the OD radical in ground and vibrationally excited states

Laser magnetic resonance spectra of the OD radical in low-lying vibrational levels of the X 2Π state have been recorded at a variety of wavelengths in the far-infrared. The spectra have been assigned to rotational and fine-structure transitions and fitted to a model Hamiltonian to determine the appropriate molecular parameters for the levels v = 0 to 3. The results are compared with those from previous studies of OD in these vibrational levels.

The far-infrared laser magnetic resonance spectrum of the SiH radical and determination of ground state parameters

The far-infrared laser magnetic resonance (LMR) spectrum of the SiH radical in the υ=0 level of its X 2Π state has been recorded. The signals are rather weak. The molecules were generated in the reaction between fluorine atoms and SiH4. Rotational transitions have been detected in both 2Π1/2 and 2Π3/2 spin components but no fine structure transitions between the spin components were observed. Proton hyperfine splittings were resolved on some lines. The measurements have been analyzed, subjected to a least-squares fit using an effective Hamiltonian and the appropriate molecular parameters determined. The weakness of the spectrum and the failure of attempts to power saturate favorable lines are both consistent with a small value for the electric dipole moment for SiH.

Far-infrared laser magnetic resonance spectrum of the AsH radical in X3Σ −

The far-infrared laser magnetic resonance spectrum of AsH in the ground X 3Σ − state has been observed using five optically pumped laser lines as sources. The AsH radical was produced by the reaction of metallic arsenic with microwave discharge products of a H 2 and O 2 mixture. From an analysis of the observed spectrum, the following rotational and fine structure constants were obtained: B 0 = 215 877.54 (23), D 0 = 9.834 (11), λ = 1 763 488 (56), and γ = −8 114.5 (60), all in MHz with 3σ in parentheses. The hyperfine coupling constants were also determined for the two nuclei as follows: α As = −11.5 (14), β As = −159.4 (13), eQq As = −97.6 (72), α H =−49.80 (66), and β H =4.15 (60), again in MHz with 3σ in parentheses.

Far-infrared laser magnetic resonance spectra of the PH and PD radicals in X3Σ −

Far-infrared laser magnetic resonance (LMR) spectra of PD in the ground vibronic state ( X 3Σ −, v = 0) were observed using the 570.6-, 380.6-, 287.3-, 232.9-, 191.6-, and 164.6-μm laser lines as sources, and the v = 1 spectrum was also observed with the 392.1-μm laser line. By combining the present results with mid-infrared LMR and optical spectroscopic data already reported, the molecular constants of PD in X 3Σ − were refined as follows: B 0 = 4.362 8675(77), D 0 = 0.000 118 03(24), λ 0 = 2.208 48(57), γ 0 = −0.039 900(34), B 1 = 4.269 248(65), λ 1 = 2.209 5(10), γ 1 = −0.038 82(21), and ν 0 = 1653.284 91(51), all in cm −1 with 3σ in parentheses. The 31P hyperfine coupling constants were determined to be α P = 0.004 330(39) and β P = −0.005 312(32) for the v = 0 state and α P = 0.004 66(40) and β P = −0.004 79(69) for the v = 1 state, again in cm −1 with 3σ in parentheses. The far-infrared LMR spectra of PH in the X 3Σ −, v = 0 state were measured on five new laser lines, and an analysis of the observed spectrum combined with that already reported yielded molecular constants much improved in precision. Using the results on both PD and PH, the equilibrium structure and the potential constants up to the fourth order were derived, where allowance was made for adiabatic and nonadiabatic corrections: r e BO = 1.42140(22) A ̊ , ω e (PH) = 2366.79(16) cm −1, a 1 = −2.3797(18), and a 2 = 3.461(14).

ChemInform Abstract: THE FAR‐INFRARED LASER MAGNETIC RESONANCE SPECTRUM OF THE METHYLIDYNE RADICAL AND DETERMINATION OF GROUND‐STATE PARAMETERS

Chemischer InformationsdienstVolume 14, Issue 39 Physical Organic Chemistry ChemInform Abstract: THE FAR-INFRARED LASER MAGNETIC RESONANCE SPECTRUM OF THE METHYLIDYNE RADICAL AND DETERMINATION OF GROUND-STATE PARAMETERS J. M. BROWN, J. M. BROWNSearch for more papers by this authorK. M. EVENSON, K. M. EVENSONSearch for more papers by this author J. M. BROWN, J. M. BROWNSearch for more papers by this authorK. M. EVENSON, K. M. EVENSONSearch for more papers by this author First published: September 27, 1983 https://doi.org/10.1002/chin.198339070AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume14, Issue39September 27, 1983 RelatedInformation

The far-infrared laser magnetic resonance spectrum of the CH radical and determination of ground-state parameters

The far-infrared laser magnetic resonance (LMR) spectrum of the CH radical in the v = 0 level of the X 2Π state was studied in detail. Nine transitions that are accessible with currently available laser lines were recorded. The measurements were analyzed and subjected to a single least-squares fit using an effective Hamiltonian. The data provide primary information on the rotational and fine-structure intervals between the lowest rotational levels. They also yield values for the Λ-type doubling and proton hyperfine splittings in the same levels.

The microwave spectrum of the PH 2 radical

Three rotational transitions, 1 10 ← 1 01, 2 20 ← 2 11, and 3 30 ← 3 21, of the PH 2 radical in the ground vibronic state were observed in the mm-wave region, by using a source-frequency modulation spectrometer with a 1-m-long free space cell. The PH 2 radical was generated directly in the cell by glow discharge in a mixture of phosphine and oxygen. Thirty four fine and hyperfine components were measured for the three transitions. An analysis of the observed spectra, combined with far-infrared and mid-infrared laser magnetic resonance spectra and laser-induced fluorescence spectra obtained by other works, improved the rotational and spin-rotation interaction constants in precision. The observed hyperfine structure gave the magnetic hyperfine coupling constants for both P and H nuclei and also the P nuclear spin-rotation interaction constants.

Far-infrared laser magnetic resonance spectrum of NHD

Far-infrared laser magnetic resonance spectra of NHD (X 2A′') (0,0,0) have been observed. Data are presented for the rotational transitions 3 13 ← 2 02 and 4 13 ← 3 22 observed at wavelengths of 211.3 and 374.1 μm respectively. Theoretical values of the transition magnetic field strengths have been calculated using the best available molecular constants. The agreement between theory and experiment confirms our spectroscopic assignments, but indicates that with further experimental data, considerable refinement of the molecular constants will be obtained.

The far-infrared Laser Magnetic Resonance Spectrum of the OH radical

The far-infrared Laser Magnetic Resonance (LMR) Spectrum of the OH radical in the v = 0 level of the X 2Π state has been studied in detail. All transitions that are accessible with currently available laser lines have been recorded. The measurements have been analyzed and subjected to a single least-squares fit using an effective Hamiltonian. The data provide primary information on the rotational and fine-structure intervals between the lowest rotational levels and the parameter values determined in the fit are A ̃ 0 = −4168.63913(78) GHz , γ ̃ 0 = −3.57488(49) GHz , B 0 = 555.66097(11) GHz, D 0 = 0.0571785(86) GHz.

Far-infrared laser magnetic resonance spectra of vibrationally excited OH and OD

Several new far-infrared laser magnetic resonance spectra of OH and OD have been detected in the reactions of H or D atoms with ozone. The strongest spectra have been assigned to rotational transitions in v= 6 OH and v= 4 OD of the X2Π3/2 state.

Far-infrared laser magnetic resonance spectrum of SeD (X 2Π [formula omitted

Far-infrared laser magnetic resonance (LMR) spectra of SeD have been detected at 513 μm using a formic acid laser, and assigned to Zeeman components of the J = 3 2 → 5 2 transition in the six isotopic forms 82,80,78,77,76,74SeD. Analysis yields the following B o constants (cm −1): 82SeD 3.96047, 80SeD 3.96284, 78SeD 3.96532, 77SeD 3.96657, 76SeD 3.96793 and 74SeD 3.97066. These values, combined with B o for 80SeH from 5.6μm LMR, yield r e = 0.14634 nm for SeD.

Far-infrared laser magnetic resonance spectrum of CH 2F

Laser magnetic resonance rotational spectra of the free radical CH 2F have been obtained using far-infrared laser lines at 301.3, 393.6, 513.0, and 567.9 μm. The radical was prepared under fast-flow conditions by fluorine atom abstraction of a hydrogen from methyl fluoride and by fluorine atom addition to diazomethane. The spectra obtained are too crowded and overlapped to permit significant spectroscopic analysis, but they do support a planar C 2 v structure for CH 2F and lead to a value of ( B + C) = 1.953 ± 0.015 cm −1.