Nuclear quadrupole coupling in the microwave spectrum of imidazole

The quadrupole hyperfine structure in the rotational spectrum of two isotopic forms of imidazole has been analyzed to obtain principal nuclear quadrupole coupling constants for the two nonequivalent nitrogen atoms. The results have been compared with field gradient tensors calculated using INDO molecular orbital wavefunctions and some implications for the electronic structure of imidazole are mentioned. Comparisons with pyrazole and the NQR results for imidazole are also made.     

Pressure broadened line widths of BrCN in the microwave region

The line widths of cyanogen bromide (BrCN) have been measured at room temperature (305 K) by using a double modulation microwave spectrograph. The self-broadening of two quadrupole hyperfine lines of the transition J = 3 → 4 has been measured. The foreign gas broadening by OCS, CO₂, N₂, CH₃CN, CH₃I, HCHO and CH₃CHO molecules has been measured only for the intense line at 32·957 GHz. These measured line widths have been compared with the calculated line widths using Anderson [6] as well as Murphy and Boggs [8] theories of pressure broadening.     

Laser spectroscopic determination of the 50V quadrupole moment

Using the method of atomic-beam magnetic resonance, detected by laser-induced resonance fluorescence (ABMR-LIRF), the atomic ground-state hyperfine intervals of ⁵⁰V were precisely measured. A quadrupole moment ratio $\text{Q(}{}^{50}\text{V}\text{) / (}{}^{51}\text{V}\text{= ?4.03(3)}$ is obtained which results in $\text{Q(}{}^{50}\text{V}\text{) = +0.21(4)}\text{b}$.     

Nuclear quadrupole coupling in the microwave spectrum of 1,2,3-triazole

The hyperfine structure in the microwave spectra of 1,2,3-triazole and N-deutero 1,2,3-triazole has been analyzed. The coupling constants derived from the analysis of each isotopic species have been combined to give the principal nuclear quadrupole coupling constants at the sites of the three inequivalent ¹⁴N nuclei.     

The molecular conformation and dipole moment of thiane from the microwave spectrum

The microwave spectrum of thiane, a heterocyclic analog of cyclohexane, has been studied in the region 26.5–40 GHz. The molecule is a highly asymmetric rotor (κ = 0.050154). From the analysis of both the a-type and c-type transitions, the rotational constants determined are (in MHz): A = 3992.719, B = 3005.812, and C = 1914.683. A study of the Stark effect has yielded the dipole moment components (in Debye units) μ_a = 1.684 ± 0.009, μ_c = 0.578 ± 0.002, which give a total dipole moment of μ = 1.781 ± 0.010. Comparison of the spectral data from tetrahydropyran, thiane, and 1,4-thioxane demonstrates the similarity in structure of these three compounds. It is found that a very reasonable set of structural parameters can be found which adequately fits the spectral data of all three molecules.     

The microwave spectrum and dipole moment of heptafulvene

The microwave spectrum of heptafulvene (C₈H₈) has been investigated in the frequency range from 26 to 40 GHz. The following rotational constants have been obtained from a least-squares fit of the measured transition frequencies: A = 3665.972(66)MHz, B = 2004.3165(59)MHz, and C = 1297.5029(90)MHz. From the corresponding moments of inertia it was concluded that heptafulvene has a planar equilibrium structure. The quantitative measurement of the Stark splittings of three transitions have yielded a dipole moment of 0.477(5) D along the a principal axis. A series of satellite transitions accompanied each rotational transition. The satellites have been assigned to the lowest out-of-plane vibration ν₄₂ (B₂) for which a frequency of 70(11) cm^?1 has been determined from relative intensity measurements.     

Dipole moment of the HO2 radical from its microwave spectrum

Stark effects are measured for the 1₀₁ ← 0₀₀, 7₁₇ ← 8₀₈, and 9₀₉ → 8₁₈ transitions of the HO₂ free radical. The unresolved Stark patterns of the b-type transitions are analyzed by the use of computer simulation. Second-order perturbation theory, including the effect of spin-doublings in the denominators, is used for the calculation of the Stark effect coefficients. The dipole moment determined is μ_a = 1.412 ± 0.033 D, μ_b = 1.541 ± 0.016 D, and μ_total = 2.090 ± 0.034 D.     

Molecular structure, nuclear quadrupole coupling constant and dipole moment of nitrogen trichloride from microwave spectroscopy

The rotational constants of four isotopic species of nitrogen trichloride have been obtained from transitions in the millimeter region. Two r_s structures have been obtained with the following average values of the parameters. rN−C1=1.7535 ± 0.0020 A.The Stark effect of the J = 3 ← 2 transition was analyzed to obtaine the value 0.39 ± 0.01 D for the dipole moment of NCl₃. The measurement of the separation of the two strongest hyperfine components of the J = 2 ← 1 transition yielded the value of −108 ± 3 MHz for the N---Cl bond axis quadrupole coupling constant.     

The microwave spectrum, structure, chlorine nuclear quadrupole coupling constants, dipole moment, and centrifugal distortion constants of dichlorosilane

The microwave spectra of three isotopic species of dichlorosilane, SiH₂Cl₂, in its ground vibrational state, have been measured in the frequency region 8–40 GHz. The spectra have yielded values for the rotational constants, centrifugal distortion constants, and chlorine nuclear quadrupole coupling constants, as well as the molecular dipole moment, 1.13 ± 0.02 D. The molecule has C_2v symmetry, and the bond lengths and angles r(Si---Cl=2.033±Å, r(Si---H)=1.480±0.015Å, (Cl---Si---Cl)=109°43′±20±, (H---Si---H)=111°18′±40′ The centrifugal distortion constants have been compared with those calculated using a published force field.     

Hyperfine structure in the Gd II spectrum and the nuclear electric quadrupole moment of157Gd

The hyperfine structure of¹⁵⁷Gd was investigated in 20 Gd II lines by means of a photoelectric recording Fabry-Perot interferometer with digital data processing. The hyperfine splitting factors,A andB, were obtained by computer fits to the observed line structures. Using a multiconfigurational set of wave functions in intermediate coupling derived by Wyart, mono-electronic hyperfine parameters were deduced by a parametric treatment. The nuclear electric quadrupole moment of¹⁵⁷Gd was evaluated from the quadrupole interaction of the 5d electron in 4f ⁷ 5d6s, the 5d electron in 4f ⁷ 5d6p, and the 6p electron in 4f ⁷ 5d6p. The three values obtained for the quadrupole moment agree very well. The final result, corrected for Sternheimer shielding, isQ(¹⁵⁷Gd) =1.34(7)·10^?24 cm².     

The microwave spectrum and quadrupole coupling in tricarbonyl(methylcyclopentadienyl) manganese

The rotational spectrum of tricarbonyl(methylcyclopentadienyl) manganese has been recorded in the range from 1–23 GHz using an FTMW spectrometer working on a molecular beam. This spectrum is assigned for the first time, yielding the rotational constants of the molecule and quartic centrifugal distortion constants. The fine structure due to the quadrupole interaction of the ⁵⁵Mn nucleus could be solved and gave the quadrupole coupling tensor (which is compared with that of tricarbonyl(cyclopentadienyl)manganese, and the spin-rotation constants. An additional splitting of a few kHz, which could be observed for some transitions, is interpreted as arising from the internal rotation of the methyl group.     

On the variation of spectral line widths within stark-broadened multiplets

The Stark broadening of isolated ion lines is considered in the electron impact approximation. It is shown by an elementary formulation of the theory that, under certain plasma conditions, situations may arise in complex atoms where a relatively small number of collision-induced transitions predominate in the broadening, and consequently where appreciable variations of spectral line width are obtained within multiplets. Such lines are then particularly suitable for application of the Stark-broadening mechanism as a means of studying atomic structure and collision physics.     

The microwave spectrum of C-fluorophosphaethyne FCP: Structure determination,dipole moment,and vibration-rotation data

The microwave spectrum of the new linear triatomic molecule C-fluorophosphaethyne FCP which is produced when CF₃PH₂ vapor passes over solid KOH at room temperature and ca. 20 μmHg pressure has been studied. Transitions belonging to the two isotopic variants ¹⁹F¹²C³¹P and ¹⁹F¹³C³¹P have been analyzed and the resulting structural data are $\text{r(}\text{FC}\text{) = 1.285 ± 0.005}\text{A}\text{?}$ and $\text{r(}\text{CP}\text{) = 1.541 ± 0.005}\text{A}\text{?}$. The study has yielded the following spectroscopic parameters for ¹⁹F¹²C³¹P: B₀ = 5257.80 ± 0.03 MHz, α₂ = ?11.95 ± 0.05 MHz, q₂ = 4.478 ± 0.002 MHz, and μ = 0.279 ± 0.001 Debye.     

The microwave spectrum and dipole moment of 1-cyano-1,3-cyclopentadiene

The microwave spectrum of 1-cyano-1,3-cyclopentadiene has been assigned and the rotational constants obtained are (in megahertz): A = 8356, B = 1904.24, and C = 1565.36. The dipole moment components were measured and are (in debye) μ_a = 4.25, μ_b < 0.3, μ_total = 4.25.     

Microwave spectrum,quadrupole hyperfine interaction,and electric dipole moment of the BrF molecule

The measurements of the microwave spectrum of BrF were carried out on the hyperfine components of J = 1 ← 0 and J = 2 ← 1 rotational transitions of ⁷⁹BrF and ⁸¹BrF. A direct diagonalization procedure of the energy matrix of the total Hamiltonian including Stark effect has been used. The following constants were derived:

     

17.

Measurements of positions, strengths and self-broadened widths of H₂O from 2900 to 8000 cm: line strength analysis of the 2nd triad bands     

Robert A. Toth 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,94(1):51-107

High-resolution spectra of H₂O were recorded with a Fourier-transform spectrometer covering H₂O transitions from 2900 to 8000 cm⁻¹. Over 13,000 absorptions were measured to determine line positions, strengths and self-broadened half-width coefficients. The H₂ ¹⁶O line strengths of the (0 3 0)-(0 1 0), (1 1 0)-(0 1 0), (0 1 1)-(0 1 0) and (0 3 0)-(0 0 0), (1 1 0)-(0 0 0), (0 1 1)-(0 0 0) bands were fitted to a quantum mechanical model which involves the interactions between the (0 3 0), (1 1 0), and (0 1 1) vibrational states. Also fitted were experimental strengths of the hot bands; (1 2 0)-(0 1 0) and (0 2 1)-(0 1 0). The model includes 14 dipole matrix elements for B- and A-type transitions. The measured line positions were used along with hot water emission measurements (for the (0 3 0), (0 4 0), and (0 5 0) states of H₂ ¹⁶O) in an analysis to obtain high-accuracy energy level values in the (0 3 0), (1 1 0), (0 1 1), (0 4 0), (1 2 0), (0 2 1), (2 0 0), (1 0 1), (0 0 2), and (0 5 0) vibrational states of H₂ ¹⁶O and the (1 1 0) and (0 1 1) states of H₂ ¹⁷O. Also included were measurements and analysis of self-broadened half-widths for over 4700 absorptions between 4405 and 7729 cm⁻¹. The results from this investigation provide new information for the noted H₂ ¹⁷O bands and present a more accurate representation of the measured H₂ ¹⁶O bands.     

18.

Spectroscopic quadrupole moment of holmium from pionic X-ray measurement     

P. Ebersold  B. Aas  W. Dey  R. Eichler  J. Hartmann  H.J. Leisi  W.W. Sapp 《Physics letters. [Part B]》1974,53(1):48-50

From the observed quadrupole splitting of the 5g-4f X-ray transition in π-¹⁶⁵Ho we determine the spectroscopic quadrupole moment of ¹⁶⁵Ho to be Q = 3.47±0.11 b. The strong interaction shift and the width of the 4f level are found to be ?₀ = 0.35±0.08 keV and Γ₀ = 0.21±0.04 keV, respectively.     

19.

Spectroscopic quadrupole moment of 23Na from muonic X-rays     

B. Jeckelmann  W. Beer  I. Beltrami  F.W.N. de Boer  G. de Chambrier  P.F.A. Goudsmit  J. Kern  H.J. Leisi  W. Ruckstuhl  A. Vacchi 《Nuclear Physics A》1983,408(3):495-506

     

20.

Microwave spectrum,structure, quadrupole coupling constants,and dipole moment of bromotrifluorosilane     

《Journal of Molecular Spectroscopy》1987,125(1):76-90

     

79BrF

81BrF

Be (MHz) 10 667.610 (60)

10 616.522 (70)

eq0Q (MHz) 1086.80 (30)

908.09 (20)

eq1Q (MHz) 1085.66 (60)

907.41

Measurements of positions, strengths and self-broadened widths of H2O from 2900 to 8000 cm: line strength analysis of the 2nd triad bands

High-resolution spectra of H₂O were recorded with a Fourier-transform spectrometer covering H₂O transitions from 2900 to 8000 cm⁻¹. Over 13,000 absorptions were measured to determine line positions, strengths and self-broadened half-width coefficients. The H₂ ¹⁶O line strengths of the (0 3 0)-(0 1 0), (1 1 0)-(0 1 0), (0 1 1)-(0 1 0) and (0 3 0)-(0 0 0), (1 1 0)-(0 0 0), (0 1 1)-(0 0 0) bands were fitted to a quantum mechanical model which involves the interactions between the (0 3 0), (1 1 0), and (0 1 1) vibrational states. Also fitted were experimental strengths of the hot bands; (1 2 0)-(0 1 0) and (0 2 1)-(0 1 0). The model includes 14 dipole matrix elements for B- and A-type transitions. The measured line positions were used along with hot water emission measurements (for the (0 3 0), (0 4 0), and (0 5 0) states of H₂ ¹⁶O) in an analysis to obtain high-accuracy energy level values in the (0 3 0), (1 1 0), (0 1 1), (0 4 0), (1 2 0), (0 2 1), (2 0 0), (1 0 1), (0 0 2), and (0 5 0) vibrational states of H₂ ¹⁶O and the (1 1 0) and (0 1 1) states of H₂ ¹⁷O. Also included were measurements and analysis of self-broadened half-widths for over 4700 absorptions between 4405 and 7729 cm⁻¹. The results from this investigation provide new information for the noted H₂ ¹⁷O bands and present a more accurate representation of the measured H₂ ¹⁶O bands.     

Spectroscopic quadrupole moment of holmium from pionic X-ray measurement

From the observed quadrupole splitting of the 5g-4f X-ray transition in π-¹⁶⁵Ho we determine the spectroscopic quadrupole moment of ¹⁶⁵Ho to be Q = 3.47±0.11 b. The strong interaction shift and the width of the 4f level are found to be ?₀ = 0.35±0.08 keV and Γ₀ = 0.21±0.04 keV, respectively.