Keith Tereszchuk

Infrared emission spectra of BeH2 and BeD2

High resolution infrared emission spectra of beryllium dihydride and dideuteride have been recorded with a Fourier transform spectrometer. The molecules were generated in a discharge-furnace source, at 1500 °C and 333 mA discharge current, with beryllium metal and a mixture of helium and hydrogen or deuterium gases. The antisymmetric stretching modes (ν3) of BeH2 and BeD2, as well as several hot bands involving ν1, ν2, and ν3, were rotationally analyzed and spectroscopic constants were determined. The equilibrium rotational constant (Be) of BeH2 was found to be 4.753 66(2) cm−1, and the equilibrium bond distance (Re) of 1.326 407(3) A was determined for BeH2.

The Far-Infrared Spectrum of Hydrogenated Amorphous Carbon and the 21, 27, and 33 Micron Features in Carbon-rich Proto-Planetary Nebulae

We report laboratory emission spectra of hydrogenated amorphous carbon (HAC) in the wavelength range 19 μm < λ < 120 μm (525-83 cm-1) at temperatures between 300°C and 500°C. These spectra show emission features at 21, 27, and ≈33 μm (475, 370, and 303 cm-1) that can be identified with similar bands in the far-infrared spectra of extreme carbon stars, proto-planetary nebulae, and planetary nebulae. It is suggested that HAC is present in these objects but that the chemical composition of this material depends on the evolutionary state. We also detect a number of broad features at wavelengths longer than 40 μm, attributable to chemical groups in HAC. A strong feature is observed at ≈60 μm (165 cm-1) in laboratory spectra and may be present in spectra of the carbon-rich planetary nebula CPD -56°8032. We briefly discuss the nature of the chemical groups responsible for the appearance of these features.

Laboratory spectroscopy of hot water near 2 microns and sunspot spectroscopy in the H-band region

The infrared spectrum of sunspots is analyzed in the H-band region (5540-6997 cm-1) with the aid of a new, hot (T = 1800 K) laboratory emission spectrum of water covering 4878-7552 cm-1. There are 682 lines in the sunspot spectrum and 5589 lines in the laboratory spectrum assigned quantum numbers corresponding to transitions due to H216O using a combination of previously known experimental energy levels for water and variational line lists. A further 201 unassigned lines common to both spectra can also be associated with water.

Emission spectrum of hot HDO below 4000 cm−1☆

Fourier transform emission spectra were recorded using a mixture of H2O and D2O at a temperature of 1500 °C. The spectra were recorded in three overlapping sections and cover the wavenumber range 1800–3932 cm−1. This spectrum is analyzed together with a previously reported one spanning the 380–2190 cm−1 range [Parekunnel et al., J. Mol. Spectrosc. 2001 (28) 101]. This analysis leads to 4409 newly assigned HDO emission lines. This work particularly extends data on the (200) and (120) states of HDO for which newly determined energy levels are presented.

Infrared emission spectra of BeH and BeD

High resolution infrared emission spectra of beryllium monohydride and monodeuteride have been recorded. The molecules were generated in a furnace-discharge source, at 1500 °C and 333 mA discharge current, with beryllium metal and a mixture of helium and hydrogen or deuterium gases. Approximately 160 BeH lines and 167 BeD lines for the vibrational bands v=1→0 to v=4→3 were observed in the spectra and spectroscopic constants were determined. The Dunham constants (Yl,m) and Born–Oppenheimer breakdown constants were obtained in a combined fit of the BeH and BeD data. The equilibrium rotational constants (Be) for BeH and BeD were found to be 10.319 59(3) cm−1 and 5.688 29(2) cm−1, respectively, while the equilibrium vibrational constants (ωe) are 2061.416(3) and 1529.956(3) cm−1. The equilibrium distance (Re) was determined to be 1.342 436(2) A for BeH.

Spatiotemporal structure of a laser beam over 144 km in a Canary Islands experiment

We analyzed the observations of scintillations in a laser beam (532 nm, ~200 mW power) traveling along a 144 km path at an altitude of 2.2-2.4 km above sea level, just above the atmospheric boundary layer, between the islands of La Palma and Tenerife. The observations were performed during nighttime on 18 July 2011, by means of a telescope with an aperture diameter of 1 m. Strong scintillations were observed. The estimates of spatial spectra and correlation functions indicated that the observed intensity fields possess, statistically, a locally isotropic structure, which agrees with the idea of a locally isotropic turbulence. The estimates of spatial autospectra and autocorrelation functions of the intensity field indicated that the characteristic scale of the internal structure of the observed clusters is 6.5-8 mm, while the characteristic size of the clusters is 4-5 cm. The major contribution to the observed scintillations comes from the inhomogeneities of the intensity field with scales from 1-2 cm up to 10-12 cm. The analysis of the cross-spectra indicated that the hypothesis of frozen turbulence introduced by Taylor can be used for the description of spatiotemporal structure of intensity fluctuations of laser beams traveling through long paths in the atmosphere.

Fourier transform emission spectroscopy of YbO in the near-infrared region☆

The emission spectrum of gas-phase YbO has been investigated using a Fourier transform spectrometer. Chemiluminescence was observed from excited YbO molecules produced in a Broida-type oven by the reaction of ytterbium metal vapor with N2O. A total of eight red-degraded bands in the range 9800–11 300 cm � 1 were recorded at a resolution of 0.04 cm � 1 . Because of the multiple isotopomers present in the spectra, only three bands were rotationally analyzed. Perturbations were identified in two of these bands and all three transitions were found to terminate at the X 1 R þ ground electronic state. The electronic configurations that give rise to

Fourier transform infrared emission spectra of BeH/BeD and BeH2/BeD2

High resolution infrared emission spectra of BeH/BeD and BeH2/BeD2 have been recorded with a Fourier transform spectrometer. Some vibrational bands of BeH/BeD and several bands of BeH2/BeD2 were rotationally analyzed, and the equilibrium structures were determined.