Sumner P. Davis

High-resolution Fourier transform spectroscopy of the Meinel system of OH

The infrared spectrum of the hydroxyl radical OH, between 1850 and 9000/cm has been measured with a Fourier transform spectrometer. The source, a hydrogen-ozone diffusion flame, was designed to study the excitation of rotation-vibration levels of the OH Meinel bands under conditions similar to those in the upper atmosphere which produce the nighttime OH airglow emission. Twenty-three bands were observed: nine bands in the Delta upsilon = 1 sequence, nine bands in the Delta upsilon = 2 sequence, and five bands in the Delta upsilon = 3 sequence. A global nonlinear least-squares fit of 1696 lines yielded molecular parameters with a standard deviation of 0.003/cm. Term values are computed, and transition frequencies in the Delta upsilon = 3, 4, 5, 6 sequences in the near-infrared are predicted.

FeH absorption in the near-infrared spectra of late M and L dwarfs

We present medium-resolution z-, J-, and H-band spectra of four late-type dwarfs with spectral types ranging from M8 to L7.5. In an attempt to determine the origin of numerous weak absorption features throughout their near-infrared spectra, and motivated by the recent tentative identification of the E 4 P–A 4 P system of FeH near 1.6 lm in umbral and cool star spectra, we have compared the dwarf spectra to a laboratory FeH emission spectrum. We have identified nearly 100 FeH absorption features in the z-, J-, and H-band spectra of the dwarfs. In particular, we have identified 34 features that dominate the appearance of the H-band spectra of the dwarfs and that appear in the laboratory FeH spectrum. Finally, all of the features are either weaker or absent in the spectrum of the L7.5 dwarf, which is consistent with the weakening of the known FeH bandheads in the spectra of the latest L dwarfs. Subject headings: infrared: stars — line: identification — molecular data — stars: low-mass, brown dwarfs

The near-infrared spectrum of the FeH molecule

The rotational analysis has been carried out on seven bands of the 4 Delta-4 Delta system of the FeH molecule. In order of wavelength of the heads they are (2-0) at 7786 A, (1-0) at 8692 A, (2-1) at 9020 A, (0-0) at 9896 A, (1-1) at 10253 A, (0-1) at 11939 A, and (1-2) at 12389 A. Molecular constants, term values, spin splittings, and Lambda-type doublings have been derived. Calculated wavelengths and wavenumbers are presented for the (2-2) and (0-2) bands with heads at 10639 and 14927 A, respectively. Finding lists of lines in the observed bands are provided to aid in astronomical applications. 19 references.

Precision Wavelengths and Energy Levels in Gold

The spectrum of gold from several different light sources has been investigated. Precision measurements have yielded new data on wavelengths and energy levels in Au i, Au ii, and Au iii. The spectrum from a high-intensity hollow-cathode lamp with a secondary discharge from an extra pair of electrodes to reduce line broadening and self-reversal was studied with a high-resolution Czerny–Turner spectrograph from 2600 to 9600 A. This study yielded an accurate line list along with information on the hyperfine structure of levels in Au i and the first observations of hyperfine splittings in Au ii. Few lines from levels with high orbital angular momentum were seen, providing information on the type of excitation in this kind of lamp. Autoionization in gold is reported for the first time, and broad lines 1–5 cm−1 wide were classified as arising from two autoionizing levels in Au i. The vacuum-ultraviolet spectrum from a condensed spark was studied, and new lines were found in Au ii and Au iii

Infrared bands of the C 2 Phillips system

The spectrum of the C2 Phillips System (A1Πu → X1∑g+) was observed in the spectral region 3300–6500 cm−1 by using a high-resolution Fourier-transform spectrometer and a hollow-cathode discharge source. Three new bands were observed, the (2–3), (1–3), and (2–4) bands belonging to the Δυ = −1 and Δυ = −2 sequences. In addition, new lines were observed in the (0–2) band. These lines, combined with previous high-resolution data, are used in a linear least-squares algorithm to calculate Dunham coefficients with a standard deviation of 0.018 cm−1. These coefficients facilitate the accurate prediction of wave numbers for the vibrational levels with υ″ and υ″.between 0 and 4.

The low‐lying electronic states of CoF

The emission spectrum of CoF has been investigated in the 820 nm–3.5 μm spectral region using a Fourier transform spectrometer. The bands were excited in a carbon tube furnace by the reaction of cobalt metal vapor and CF4 at a temperature of about 2300 °C. The bands observed in the 3000–9000 cm−1 region have been classified into three new transitions. The bands with 0‐0 R‐heads at 3458 cm−1, 3759 cm−1, and 4012 cm−1 have been assigned as the 3Δ1–3Φ2, 3Δ2–3Φ3, and 3Δ3–3Φ4 subbands of the C 3Δ–X 3Φi electronic transition. To higher wave numbers, two bands with R‐heads at 8396 cm−1 and 8565 cm−1 have been assigned as the 3Δ2–3Φ3 and 3Δ3–3Φ4 subbands of the D 3Δ–X 3Φi transition. In addition, the bands with R‐heads at 6339 cm−1 and 6542 cm−1 have been assigned as the 0‐0 3Φ4–3Δ3 and 3Φ3–3Δ2 subbands of the G 3Φ–C 3Δ transition. The G 3Φ–X 3Φ transition has been reported previously as the [10.3]3Φ–X 3Φ transition. The rotational analysis of many bands of these transitions has been obtained and the molecular co...

Infrared spectra of hot HF and DF

New Fourier transform emission measurements were obtained for HF and DF at a temperature of 2300°C. Both pure rotation and vibration-rotation lines were measured with a precision of about 0.0005 cm-1. These new lines were combined with previously measured data to give improved rotational constants for the vibrational levels υ = 0-5. The HF molecule is the most convenient monitor of 19F abundances in cool stars.

Hyperfine Structures, Isotope Shifts, and Nuclear Moments of Hg 195 , Hg 195 m, and Hg 194 †

The hyperfine structures of five lines in the optical spectra of Hg195, Hg195m, and Hg194 have been investigated under high resolution. The nuclear moments, calculated from ratios of hyperfine splittings, are μ(195m) = −1.060 ± 0.01 nm, Q(195m) = 1.5 ± 1 b, and μ(195) = +0.526 ± 0.005 nm. Isotope shifts measured relative to Hg196 were found to be Δ(195–196) = +77.2 ± 5 mK, Δ(195m–196) = +92.6 ± 5 mK, and Δ(194–196) = +143 ± 10 mK. The last result is not in agreement with published measurements. Further investigation is required before a theory can be considered applicable.

TIO MOLECULAR EMISSION IN THE SPECTRUM OF VY CANIS MAJORIS.

Relative line strengths in the rotational structure of the (0-0) band of the gamma-prime system of TiO seen in emission in the spectrum of VY CMa yields a rotational temperature close to 600 K. This is intermediate between the temperatures found by Herbig in 1962 and 1966 which are 380 and 820 K, respectively. It is also in reasonable accord with the theoretical conclusion of Schwartz that the outer boundary of the circumstellar envelope is 300 K.

Infrared emission band spectrum of Si 2

A strong infrared emission band spectrum of Si2 was observed in the region between 4500 and 6500 cm−1. It consists of 21 red-degraded bands, which are transitions between two newly observed low-lying singlet states d1Σg+–b1Πμ. The bands arise from transitions between vibrational levels from 0 to 6 in both electronic states. Rotational lines up to J = 162 were observed. A global fit was made to 2000 spectral lines, and fits were made to individual branches of each band. The source was a King-type furnace charged with SiC, filled with helium at a pressure of 100 Torr, and maintained at a temperature of 2700 K. The spectrometer was the Fourier-transform instrument at the National Solar Observatory (Kitt Peak).