A Uranium Atlas In Ascii Format, 20000 - 27000 Cm^−1

Abstract

This work was motivated by difficulties encountered while trying to calibrate laser excitation spectra, taken in short (1 {cm$^{-1}$}) scans around 438 nm, by matching optogalvanic transitions from a Uranium-Argon hollow cathode lamp to peaks listed in a widely-circulated `informal report' on the Uranium spectrum (11000~--25900 {cm$^{-1}$}) from Los Alamos\footnote{An atlas of uranium emission intensities in a hollow cathode discharge; Palmer, Keller \& Engleman, Los Alamos report LA 8251-MS, (1980)}. Short pieces of excitation spectra often fell between secure calibration lines, because many of the weaker features had been excluded from the printed linelist. To remedy this, we have re-recorded emission from a commercial Uranium hollow-cathode lamp 19800~--~27400 {cm$^{-1}$} on a Fourier transform spectrometer, at an instrumental resolution of at 0.04 {cm$^{-1}$}. The wavenumber scale was fine-tuned to match earlier reference data$^{a}$\footnote{Comparing the emission spectra of U and Th hollow cathode lamps, and a new U line list; Sarmiento $et ~al.$, A \& A, \underline{618}, A118, (2018)}\footnote{Uranium and iodine standards measured by means of Fourier-transform spectroscopy; Gerstenkorn, $et ~al.$, A \& A, \underline{58}, 255-66, (1977)} to within 0.003 {cm$^{-1}$}. This spectrum (together with its peak list) is proposed in ascii format\footnote{A uranium atlas, from 365 to 505 nm; Ross $et ~al.$ J Mol Spectrosc , \underline{369}, 111270, (2020)} as a possible aid to calibration of laser excitation spectra in the blue, violet and near UV. It extends the spectrum reported by Sarmiento and co-workers$^{b}$ that focused on calibration of astronomical spectrographs in the near IR and visible.