The hyper-Raman spectrum of CsI

The hyper-Raman spectrum of CsI has been measured by the single channel method. Two lines corresponding to the transverse and longitudinal optic phonons at the centre of the Brillouin zone could be clearly observed. Nonlinear processes competing with hyper-Raman scattering are discussed.     

The microwave spectrum of vinylcyclopropane

Frequencies of rotational transitions in the microwave region are reported for the ground and three torsionally excited states of the species of vinylcyclopropane in which the vinyl group is trans to the cyclopropane ring and there is a plane of symmetry. Transitions in the species with ¹³C substitution at the out-of-plane carbon site are also reported. An extensive search for transitions belonging to another species was not successful. The torsional excitation energy is estimated from relative intensity measurements to be 125 cm^?1. The dipole moments determined from the Stark effect ar μ_a = 0.486 ± 0.007 D, μ_c = 0.110 ± 0.010 D and μ = 0.498 ± 0.007 D.     

The millimeter-wave spectrum of trimethylphosphine

Millimeter-wave rotational spectra have been recorded for trimethylphosphine in its ground and some excited vibrational states. The l-resonance in two of the degenerate vibrations has been analyzed in detail. Internal rotation effects in one of these states are described.     

The rotational spectrum of trichlorofluoromethane

The microwave and millimetre-wave spectra of CF³⁵Cl₃ have been measured in the ground and first excited doubly degenerate (E) vibrational states. Rotational, centrifugal distortion, and quadrupole parameters were obtained for both states. In the E state, strong l-resonance was observed, enabling some rotation-vibration parameters to be accurately determined. In addition, there was a splitting of the (kl − 1) = ± 1 lines due to the asymmetry of the individual quadrupole coupling tensors with respect to the principal inertial axes.     

The infrared spectrum of GeO

The high-temperature infrared spectrum of the Δv = 1 sequence of GeO has been investigated from 882 to 955 cm⁻¹ with a tunable diode laser spectrometer. Transitions from ⁷⁰Ge¹⁶O, ⁷²Ge¹⁶O, ⁷³Ge¹⁶O, ⁷⁴Ge¹⁶O, and ⁷⁶Ge¹⁶O were measured for vibrational transitions from v = 1−0 to v = 6−5 and fit to a single set of eight Dunham potential coefficients.     

The spectrum of permutation orbifolds

We study the spectrum of permutation orbifolds of 2d CFTs. We find examples where the light spectrum grows faster than Hagedorn, which is different from known cases such as symmetric orbifolds. We also describe how to compute their partition functions using a generalization of Hecke operators.

     

The absorption spectrum of beryllium

Energy terms, dipole oscillator strengths and photoionization cross-sections from the ground state are calculated. Autoionizing state transition energies and line widths for the ¹P⁰ resonances in the continuum are also obtained. The configuration interaction method for initial and final states is used, and atomic orbitals are generated through angular-momentum-dependent, scaled Thomas-Fermi-Dirac potentials.     

The microwave spectrum of cyanoformamide

The spectrum of cyanoformamide, NCCONH₂, has been measured between 18 and 40 GHz using a Hewlett-Packard spectrometer with Stark modulation. The molecule is somewhat unstable and could most conveniently be measured in a flow system. The quadrupole hyperfine structure due to the two nitrogen nuclei has been analyzed for the ground state, and quadrupole coupling constants, rotational constants, and centrifugal distortion constants have been determined for the ground state. A rough determination of the components of the electric dipole moment was possible from the Stark shifts of suitable transitions.     

The infrared spectrum of methylenimine

Eleven isotopic species of methylenimine have been prepared by the mercury-arc photolysis of methyl azide isolated in argon, nitrogen, and carbon dioxide matrices at 4 and at 14 K. Sufficient concentrations of methylenimine were obtained for identification of all of the vibrational fundamentals except the NH stretching mode. Using a recent ab initio structural calculation for this molecule, it has been possible to derive a set of valence-force potential constants which provide a satisfactory fit to all of the infrared spectroscopic data. The magnitude of the carbon-nitrogen stretching force constant is appropriate for a double bond. The temperature dependence of the thermodynamic properties of methylenimine has also been calculated.     

The emission spectrum of HgI

The ultraviolet emission systems of HgI—C → X, D → X, F₃ → X, G → X, and H → X—are photographed and analyzed using tesla-discharge sources containing isotopically pure ²⁰⁰Hg. The previous assignment for F₃ → X is revised, the main change being a decrease by 3 units in the v″ numbering. Results for the other systems corroborate the existing interpretations, except that for C → X there are prominent intensity gaps in the unresolved rotational structure of the bands, not reported previously for “natural” HgI spectra. These gaps are attributed to perturbations of the C state by high levels (v ≈ 90) of the B state. The data for these systems are combined with existing B → X data for ²⁰⁰Hg¹²⁷I and ²⁰⁰Hg¹²⁹I and fitted simultaneously to yield optimal vibrational parameters for all states. In this analysis the X state is fitted to a mixed representation—a polynomial in ( ) for v ≤ 20 and a near-dissociation expansion for v ≥ 20, with G_v and its first derivative constrained to be continuous at v = 20. The revised estimate of _e for X is 2800 ± 40 cm⁻¹. The recommended vibrational parameters (cm⁻¹) for v ≤ 20 are ω_e = 125.41, ω_ex_e = 1.009, ω_ey_e = −0.0159.     

The microwave spectrum of trioxaadamantane

The microwave spectrum of 2,8,9-trioxaadamantane has been investigated in the region from 12.4 to 26.5 GHz. The observed spectrum exhibited the expected symmetric top pattern, with the rotational constant B₀ = 1848.64 MHz. Numerous weaker lines were observed and were attributed to vibrational satellites of the main rotational transition. The transitions from J = 3 → 4 through J = 6 → 7 were studied and no centrifugal distortion effects were observed.A structure is derived that is consistent with the observed rotational constants of the normal and one isotopic species by use of the method of diagnostic-least-squares.The second order stark effect for the K = 0 state yielded a dipole moment of 3.01 ± 0.03 D.     

The microwave spectrum of tetrazole

Microwave spectra of tetrazole and the two singly deuterated tetrazole species have been assigned. Dipole moment measurements suggest that the tautomeric form observed in normal tetrazole and N-deuteriotetrazole is 2H-tetrazole while that observed in C-deuteriotetrazole is 1H-tetrazole. All three species are planar.     

The spectrum of Wess-Zumino-Witten models

We consider the SU(2) and SO(3) Wess-Zumino-Witten models in the Schrödinger representation. Wave functions are sections of a line bundle over a loop group. We compute the spectrum of irreducible lowest weight representations appearing in the model. Fusion rules of the operator product expansion are also discussed.