The millimeter wave spectrum of phosphorus oxychloride

Millimeter wave rotational spectra of phosphorus oxychloride (OPCl₃) in the ground and excited vibrational states have been recorded and analyzed. The v₅ = 1 and v₆ = 1 state spectra show large splittings due to l resonance and the effect of the 2, -1 term r_t. Coriolis constants have been obtained for the two lowest degenerate states. The spectra of the asymmetric top species OP³⁵Cl₂³⁷Cl have been analyzed and centrifugal distortion constants obtained. These have been used to determine the harmonic force field of the molecule.     

The vacuum ultraviolet absorption spectrum of diatomic calcium

Calcium granules (99.5%) have been heated to 615°C in a tantalum furnace and the absorption spectrum has been observed on the SA 61 beam line of SUFERACO (Orsay) using a 3-metre Balzers monochromator down to the -LiF cut-off (1015 Å). An intense Rydberg series has been observed between 1900 and 1500 Å. This series extends from n = 5 to n = 12 and gives the ionization potential at 63068 cm^?1 (1585.6 Å) or 7.819eV and the quantum defect δ = 1.73.     

The submillimeter wavelength spectrum of methanol

Observations and assignments of some of the absorption lines in methanol from 200 to 850 GHz are reported. A simple phenomenological model is described which allows interpretation of spectra and prediction of new lines with little computational effort.     

The millimeter wave rotational spectrum of lactic acid

The results of a comprehensive investigation of the rotational spectrum of lactic acid over the frequency region 171-318 GHz are reported. Some supersonic expansion measurements at 8-16 GHz have also been made. A complete set of octic level constants in the asymmetric rotor Hamiltonian has been determined for the ground vibrational state from a fit to over 1000 measured transition frequencies. Spectroscopic constants have also been determined for the first five excited states of the low frequency, 60 cm⁻¹, torsional vibrational mode, and for four other vibrationally excited states. Vibrational states become rather crowded above 200 cm⁻¹, with seven different states only in the next 100 cm⁻¹, and almost all of the measured states in this energy region show evidence of perturbations. The analysis was carried out with the newly developed AABS software package for Assignment and Analysis of Broadband Spectra.     

The millimeter wave rotational spectrum of pyruvic acid

The rotational spectrum of pyruvic acid has been investigated for the first time in the millimeter-wave region, at 160-314 GHz, and also in supersonic expansion, at 10-17.4 GHz. The analysis of the broadband spectra recorded in this work was carried out with the newly developed AABS software package for Assignment and Analysis of Broadband Spectra, and precise spectroscopic constants are reported for the ground state, the first excited state of the low-frequency skeletal torsional mode ν₂₄, and the first excited state of the methyl torsional mode ν₂₃. Limited results have also been obtained for several higher excited states. The dataset for the ground state currently exceeds 1500 lines and for both the A and E internal rotor sublevels spans the complete range of values of K_a at the mid values of J for the measured transitions. The results were analysed with three freely available computer programs employing different strategies for dealing with internal rotation and a comparative discussion of their merits is made.     

The millimeter wave spectrum of the CO dimer

The millimeter wave spectrum of the isotopically substituted CO dimer, (¹³C¹⁶O)₂, has been studied for the first time, confirming and extending a recent infrared study. Eighty-seven transitions in the 77-180 GHz region have been assigned and analyzed in terms of a model-independent term value scheme involving 57 rotational levels with J=0-8. The levels can be classified into 7 “stacks” which have symmetry classifications of either A⁻/B⁺ or A⁺/B⁻ and K-values of either 0 or 1. For the normal isotope, symmetry and nuclear spin statistics cause alternate rotational levels to be missing, but for (¹³C¹⁶O)₂ all levels are present with an intensity alternation of 1:3 between A and B symmetries. The four A⁻/B⁺ stacks have not previously been observed, and the lowest of them establishes the tunneling splitting of (¹³C¹⁶O)₂ to be 3.769 cm⁻¹, slightly larger than the (¹²C¹⁶O)₂ value of 3.731 cm⁻¹. A large amount of precise experimental data is now available for the CO dimer, which should lead to greater theoretical insight into its structure and tunneling dynamics.     

The millimeter wave spectrum of tertiary butyl fluoride

Rotational spectra of tertiary butyl fluoride (TBF) in the ground and excited vibrational states have been recorded and analyzed. The excited state spectra show large splittings due to l resonance and the effect of the 2, -1 term r_t. Coriolis constants have been obtained for the three lowest degenerate states. An accidental resonance enabled the determination of the axial rotational constant of TBF.     

Pulse surface wave generator of millimeter band wavelength

Theoretical and experimental studies of high-power, relativistic surface-wave microwave Cherenkov generators are briefly considered. Some simulation and experiment results included, the experimentation being made in mm-wave region.     

The millimeter and submillimeter rotational spectrum of 1,3-dihydroxyacetone

Recent detection of the 2C sugar glycolaldehyde in the Sgr B2(N-LMH) hot core source as well as the presence of several sugars and other polyhydroxylated species in the Murchison meteorite have led to interest in observational searches for higher order sugars in the interstellar medium. 1,3-Dihydroxyacetone, the simplest 3C sugar, is one of the species detected in Murchison and is of considerable importance for observational searches as the next step in complexity for interstellar sugars. However, little spectroscopic information is available for this molecule. We present here the Doppler-limited rotational spectrum of 1,3-dihyroxyacetone to 450 GHz. Assignments include the ground state up to J=104 and four additional vibrational states. Standard rotational and quartic centrifugal distortion constants have been determined for each of these states.     

The emission spectrum of the diatomic radical, phosphorus selenide

The emission spectrum of the PSe radical is reported for the first time. Seventy-eight reddegraded bands in the region 4000–6500 Å have been measured and assigned to the A²Π-X²Π transition of PSe. Isotope shifts observed for some bandheads have been utilized in deriving the vibrational numbering. The molecular constants have been determined as (in units of cm⁻¹): ω′ = 406.9, ω′_eχ′_e = 1.3, ω″ = 556.9, ω″_eχ″_e = 1.3, and T_e = 19477.3 for the ²Π_1/2 states; and ω′_e = 402.4, ω′_eχ′_e = 1.5, ω″_e = 556.8, ω″_eχ″_e = 1.6, and T_e = 19178.0 for the ²Π_3/2 states.     

具有在位势的一维双原子链晶格振动的长声学波图像

通过数值求解具有在位势的一维双原子链晶格振动的运动方程组,给出了具有不同大小在位势的长声学波振动模图像,直观展示出在位势使原胞中两种原子的振动位移不同,并且随在位势的增大,振动位移之差显著增大.     

A millimeter wavelength radiation source using a dual gratingresonator

A novel means of producing coherent radiation by passing an electron through a dual-grating resonator is presented, The observed radiation is in accordance with the Smith-Purcell dispersion relation for a single grating. Feedback is provided by a second grating. Experiments carried out at beam energies from 30-55 keV produced radiation at wavelengths from 6 to 0.75 mm. Power measurement were used to clarify the grating beam interaction, Indications are that operation could be easily extended to shorter wavelengths to provide an inexpensive and compact radiation source in the far-infrared     

Snow cover radiometry in the near millimeter wavelength range

The results of field and laboratory measurements of the thermal emission of the snow cover at wavelengths 1.3–0.87, 2.2, and 3.3 mm are presented. The potential of this wavelength range for sounding the boundaries and top layer condition of the snow cover, including the melting state, is analyzed and the results of the sounding are reported. Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 9, pp. 1113–1125, September, 1997.     

On the electronic spectrum of the diatomic molecular ion

Discrete eigenvalues of the electronic Hamiltonian with dilatation analytic potentials for ionized diatomic molecules are shown to depend smoothly on the distancer of the nuclei forr finite and non vanishing. Furthermore the spectrum is analyzed atr=0 andr=∞ and the eigenvalues turn out to be continuous.     

Microwave spectrum and hyperfine structure in the rotational spectrum of diatomic gallium iodide

The J = 3←2 rotational transition of diatomic GaI molecule has been measured in the microwave region. The molecules were produced by a reaction of gallium and lead iodide in the heated zone of a splitted wave guide. The lines were observed in the 10-GHz frequency region at a reaction temperature 270–350°C. Molecular parameters have been derived for ⁶⁹Ga¹²⁷I and ⁷¹Ga¹²⁷I from the analysis of the hyperfine structure. Systematic variations in quadrupole coupling constants in III_a halides have been observed. Vibrational dependence of the nuclear quadrupole interaction for ⁶⁹Ga¹²⁷I can be written as follows: $\text{eq}{}_{\mathrm{<mtext>v</mtext>}}\text{Q(}{}^{69}\text{Ga}\text{) = ?81.29(25) + 0.43(30)(v +}\text{1}\text{2}\text{)}\text{MHz}$, $\text{eq}{}_{\mathrm{<mtext>v</mtext>}}\text{Q(}{}^{127}\text{I}\text{) = ?369.35(10) ? 2.54(16)(v +}\text{1}\text{2}\text{)}\text{MHz}$.     

The optical constants of indium antimonide at 1.5K in the near millimeter wavelength region

The results of a determination of the optical constants of n-type indium antimonide at 1.5K in the spectral region between 4 and 40 cm^–1 are presented. The absorption spectrum was determined by the two thickness method, while the refraction spectrum was determined both by an extension of the two thickness method and by an analysis of a channel spectrum. The errors involved in the application of these approximate methods are discussed. The material measured was of detector quality and, therefore, the results are relevant to the design of near millimetre wavelength detectors with optimised performance.Gong Ya-Qian is on leave of absence from Shanghai Institute of Applied Physics