Far-infrared Laser Magnetic Resonance Spectrum Research Articles

Assignment of far-infrared laser magnetic resonance spectrum of CH 2Br radical at 447.3 and 672.1 μm

Assignment of far-infrared laser magnetic resonance spectrum of CH 2Br radical at 447.3 and 672.1 μm

Part of the far-infrared laser magnetic resonance spectrum of the HF + free radical

Transitions between the spin-rotational levels of the HF + radical in the v=0 level of the X 2Π ground state have been observed by the technique of laser magnetic resonance at far-infrared wavelengths. Because of the large spin–orbit coupling in this 2Π state, the detection of the fine-structure transitions required the use of very short-wavelength laser lines (down to 40 μm). These observations have provided accurate information on the 19F hyperfine splittings in rotational levels of the upper 2 Π 1/2 spin component for the first time which has enabled the complete determination of the hyperfine structure for this molecule. An effective Hamiltonian was used to model the experimental measurements; this provided considerably more accurate values for the various molecular parameters than previously available. Using these parameters, predictions of the transition frequencies between the low-lying spin-rotational levels of the radical at zero magnetic field have been made.

The far-infrared laser magnetic resonance spectrum of the 13CH radical

Transitions between the spin-rotational levels of the 13CH radical in the v=0 level of the X 2 Π ground state have been detected by the technique of laser magnetic resonance at far-infrared wavelengths. These measurements have been combined with the previous measurements of the lambda-doubling intervals of the molecule [J. Chem. Phys. 85 (1986) 1276 ] to determine an improved set of molecular parameters for 13CH. The analysis provides accurate predictions of the transition frequencies between the low-lying spin-rotational levels of the radical at zero magnetic field. A comparison is made with the values of the corresponding parameters of 12CH which reveals small effects due to the breakdown of the Born–Oppenheimer approximation.

Far-infrared detection of $^{\mathsf{17}}$OH towards Sagittarius B2

The frequencies and line strengths of the 2 Π3/2 J = 5/2-3/2 rotational transition of 17 OH have been calculated from an analysis of its far-infrared laser magnetic resonance spectrum. These results have been used to make the first detection of a pure rotational transition of 17 OH in the ISM. Two resolved components of this transition appear in absorption towards the giant molecular cloud Sagittarius B2, which was observed at a spectral resolution of 33 km s −1 with the Fabry-Perot mode of the ISO Long Wavelength Spectrometer. The corresponding transition of 18 OH was also observed and its line shape was modelled using H  measurements. The 18 O/ 17 O ratio of 3.5 was then used to compare this with the observed 17 OH line shape.

Studies of the mid- and far-infrared laser magnetic resonance spectra of the CD radical: information on vibrationally excited levels

Two separate studies of the CD radical in vibrationally excited levels of its X 2 Π ground state have been made by the technique of laser magnetic resonance. The first of these studies was in the far-infrared; rotational transitions of CD in the v = 1 and 2 levels have been detected. The second study was carried out in the mid-infrared using a carbon monoxide laser magnetic resonance spectrometer. In these experiments, transitions in the (1,0), (2,1), and (3,2) bands have been detected. All the available data on CD in its X 2 Π state have been used to determine an improved set of molecular parameters for the CD radical. In addition to the above data sets, previous far-infrared laser magnetic resonance on the CD radical in the v = 0 level and FTIR observations of the (1,0) and (2,1) bands have been included. The principal molecular parameters determined are: ν 0 = 2032.03360 ( 18 ) cm - 1 , ω e x e = 34.72785 ( 58 ) cm - 1 , B 0 = 7.7018632 ( 14 ) cm - 1 , α B = - α e = - 0.212239 ( 11 ) cm - 1 , where the figures given in parentheses are one standard deviation from the least squares fit. A small but significant dependence of the orbital contribution to the magnetic dipole moment on the vibrational quantum number is detected. This may reflect the mixing between the X 2 Π and a 4 Σ - states of CD.

Analysis of far-infrared laser magnetic resonance spectra of CH 2 Br at 447.3 and 671.1µm

A simple model has been developed to describe the Zeeman patterns of far-infrared laser magnetic resonance spectra of the monobromomethyl radical CH2Br observed at 447.3 and 671.1mum. A satisfactory agreement between the experimental spectra of the radical and their simulation with this simple model has been achieved. This approach can be used to gain further information about the structure and the spectrum of this interesting radical.

Far-infrared LMR spectroscopic investigation of the quasi-linear molecule DCCN: The v5(1 0) transition

The far-infrared laser magnetic resonance spectrum (FIR LMR) of the v5 bending vibrational transition of DCCN in its X3 Σ– state is reported. The DCCN radical was produced inside the spectrometer cavity by the reaction of deuterated acetonitrile with F atoms. DCCN resonances were measured on seven laser lines. Nitrogen hyperfine structure was observed on a number of the resonances. The analysis provides improved accuracy for the separation v5= 1 [Formula: see text] 0 and some of the 14N hyperfine coupling constants for this isotopomer.PACS No.: 33.20Ea

The Far-Infrared Laser Magnetic Resonance Spectrum of CH2F

Far-infrared laser magnetic resonance (FIR-LMR) spectra due to the CH2F radical have been recorded on seven laser lines at wavelengths between 301 and 568 μm. Observed resonances were assigned to fine and hyperfine components of pure rotational transitions of CH2F in the ground vibrational state and the first excited state of the ν4out-of-plane bending mode. All assigned transitions obeya-dipole selection rules. The data were combined with previously reported microwave results (Y. Endo, C. Yamada, S. Saito, and E. Hirota,J. Chem. Phys.79, 1605 (1983)) and subjected to a least-squares fit to determine the parameters of the effective Hamiltonian describing thev4= 0 and 1 vibrational levels of the CH2F radical.

Laser Magnetic Resonance Measurement of the [TSUP]3[/TSUP][ITAL]P[/ITAL][TINF]1[/TINF]–[TSUP]3[/TSUP][ITAL]P[/ITAL][TINF]0[/TINF] Fine-Structure Separation of P[TSUP]+[/TSUP

The far-infrared laser magnetic resonance spectrum associated with the J = 1 ← 0 fine-structure transition of 31P+ in its ground 3P state has been recorded. This is the first laboratory observation of this magnetic dipole transition, and its frequency has been measured 2 orders of magnitude more accurately than the previous, indirect determination from optical spectroscopy. The frequency is ΔE10 = 4944433.0 ± 1.7 MHz. A small nuclear hyperfine splitting was also observed for the J = 1 level.

Identification and Analysis of the Far-Infrared Laser Magnetic Resonance Spectrum of the HS 2 Radical

The first observation of the far-infrared laser magnetic resonance spectrum of the HS 2 radical in its ground 2 A″ state is reported. The radical was produced in the gas-phase reaction between fluorine atoms and hydrogen sulfide, H 2S. Spectra associated with several different rotational transitions (with values of N up to 30 and K a up to 4) have been identified and analyzed to give an improved set of molecular parameters. In particular, the value for the centrifugal distortion constant Δ K of 24.339(10) MHz is significantly different from the value assumed by S. Yamamoto and S. Saito ( Can. J. Phys. 72, 954 (1994)) in their earlier millimeter-wave study, Zeeman parameters have also been determined.

Far-Infrared Laser Magnetic Resonance Spectroscopy of CH2Cl (X̃2B1)

Far-infrared laser magnetic resonance (FIR-LMR) spectra of CH235Cl (X̃2B1) observed at three FIR wavelengths in the range 450 μm ≤ λ ≤ 750 μm have been analyzed and assigned. The spectra were obtained using three different source reactions, F + CH3Cl → CH2Cl + HF, Cl + CH2CO → CH2Cl + CO, and Na + CH2Cl2 → CH2Cl + NaCl. The resonances at the three FIR wavelengths were attributed to a-dipole transitions involving relatively high rotational states (12 ≤ N ≤ 20 and 2 ≤ K ≤ 6). The spectra could be simulated satisfactorily based upon the molecular parameters derived by Endo et al. [Can. J. Phys. 62, 1347-1360 (1984)] from the millimeterwave spectrum of much lower rotational states of the radical. The agreement which was obtained shows that the CH2Cl radical possesses a rather rigid structure.

Laser magnetic resonance spectra of 14N34S (X 2Π32) at 570.6 μm

Abstract Far-infrared laser magnetic resonance (FIR LMR) spectra of 14N34S (2Π 3 2 ) have been observed. Data are presented for the Zeeman components of the rotational transition J = 10.5 → 11.5 observed at 570.6 μm using a methanol laser. Theoretical values of the transition magnetic field strengths have been calculated using the best available molecular constants. The agreement between theory and experiment confirms the spectroscopic assignments.

A Measurement of the J = 2 1 Fine-Structure Interval for 28Si and 29Si in the Ground 3P State

We report the first observation of the far-infrared laser magnetic resonance spectrum associated with the J = 2 c 1 fine-structure interval of Si and 29Si in the 3P ground state. In Si this separation is 4378.3280(2) GHz, and for 29Si it is 4378.3306(6) GHz. The magnetic hyperfine parameter A, has also been determined for *'Si, apparently for the first time. The value obtained corresponds to a value for the electronic expectation value (T-~), of 1.626 x 1031 m-3. Zero-field transition frequencies for the hyperfine components of the J = 2 t 1 transition in 29Si are determined and will aid in their identification in interstellar sources. Subject headings: atomic data - line: identification

The fine-structure intervals of (N-14)+ by far-infrared laser magnetic resonance

view Abstract Citations (32) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Fine-Structure Intervals of 14N + by Far-Infrared Laser Magnetic Resonance Brown, John M. ; Varberg, Thomas D. ; Evenson, Kenneth M. ; Cooksy, Andrew L. Abstract The far-infrared laser magnetic resonance spectra associated with both fine-structure transitions in (N-14)+ in its ground P-3 state have been recorded. This is the first laboratory observation of the J = 1 left arrow 0 transition and its frequency has been determined two orders of magnitude more accurately than previously. The remeasurement of the J = 2 left arrow 1 spectrum revealed a small error in the previous laboratory measurements. The fine-structure splittings (free of hyperfine interactions) determined in this work are (delta)E10 = 1461.13190 (61) GHz, (delta)E21 = 2459.38006 (37) GHz. Zero-field transition frequencies which include the effects of hyperfine structure have also been calculated. Refined values for the hyperfine constants and the gJ factors have been obtained. Publication: The Astrophysical Journal Pub Date: June 1994 DOI: 10.1086/187387 Bibcode: 1994ApJ...428L..37B Keywords: Far Infrared Radiation; Fine Structure; Interstellar Matter; Magnetic Resonance; Hyperfine Structure; Nitrogen; Astrophysics; ATOMIC DATA; LINE: IDENTIFICATION; ISM: ATOMS; RADIO LINES: ISM full text sources ADS | data products SIMBAD (1)

The far-infrared laser magnetic resonance spectrum of the SH radical

We have extended the observations in the far-infrared laser magnetic resonance spectrum of the SH radical in its ground 2Π state to cover the first three rotational transitions in the 2 Π 3 2 component. Signals were seen from all naturally occurring isotopes of sulfur except the least abundant, 36S (0.02%). The measurements have been analyzed, together with selected data from previous work, to determine an improved set of molecular parameters for 32SH in its ground state. The implications of these parameters are discussed. The magnetic and electric nuclear hyperfine parameters for 33SH are significantly improved over previous work. The frequencies of rotational transitions in 32SH in the absence of a magnetic field are calculated from the parameter set to aid in the detection of this radical in astrophysical sources.

Detection of the HCS radical by far-infrared laser magnetic resonance

New far-infrared laser magnetic resonance (LMR) spectra from a free radical containing sulfur have been detected in reactions of fluorine, chlorine and hydrogen atoms with several thio-molecules. The same radical is also produced in the chain reaction between molecular fluorine and (CH3)2S2, (CH3)2S and mercaptan. The most extensive and intense LMR spectra were observed on the 108 µm D2O laser line. Based on chemical tests, isotopic substitution and qualitative spectroscopic considerations these spectra are assigned to the HCS radical. This is the first experimental observation of this radical in either the gas or condensed phases.

Far-infrared laser magnetic resonance spectrum of SO in the X3Σ − state

Far-infrared laser magnetic resonance spectrum of SO in the X3Σ − state

Molecular parameters of chromium hydride in its X6Σ + state determined by far-infrared laser magnetic resonance spectroscopy

The far-infrared laser magnetic resonance spectrum of the CrH radical in the v = 0 level of its X 6Σ + state has been studied in detail. Signals associated with the five lowest rotational transitions have been detected. Nearly 500 resonances for 52CrH have been assigned and used to determine molecular parameters which describe the rotational energy, the fine and proton hyperfine splittings, and the Zeeman effect. These parameters are well determined and their implications for the structure of CrH are discussed. A fourth-order correction to the spin-spin coupling has been identified for the first time. Precise zero-field rotational transition frequencies have been calculated which may allow the detection of the CrH radical in the interstellar medium.

Avoided crossings in the far-infrared laser magnetic resonance spectrum of HCO

Several transitions in the far-infrared spectrum of the HCO radical have been detected by the technique of laser magnetic resonance (LMR). The spectra have been assigned to both a- and b-dipole transitions and have been fitted together with previous microwave, millimeter-wave, and infrared measurements to determine a full set of parameters for HCO in its ground state. In particular, signals arising from the avoided crossing of the levels 8 08 and 7 16 in a magnetic field have been analyzed and used to determine values for the off-diagonal components of the spinrotation, proton dipolar hyperfine, and anisotropic g-tensors which are responsible for the mixing of the states. The reduced spin-rotation parameter ( ϵ ̃ ab + ϵ ̃ ba ) has been separated into its component parts by the imposition of the constraint ϵ ab ϵ ba = A B .

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

The far-infrared laser magnetic resonance spectrum of the CD radical in the v = 0 level of the X 2Π state has been studied in detail. Twelve transitions which 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 intervals. They also yield values for the Λ-type doubling and deuteron hyperfine splittings in the same levels. Combination of the measurements with the corresponding data for CH allows the two parameters, γ and A D, to be determined separately.