A spectroscopic study of atomic oxygen (O i) is performed using the Fourier-transform vacuum ultraviolet (VUV) spectrometer at the Dichroïsme Et Spectroscopie par Interaction avec le Rayonnement Synchrotron beamline of the SOLEIL synchrotron. Transition frequencies of O i lines in the range between 76,000 and 151,000 cm−1, corresponding to wavelengths between 665 and 1306 Å, are presented. In the wavelength window a data set of 208 lines is obtained for which line centers were determined at an accuracy of ≤0.035 cm−1, verified through a comparison with previous VUV-laser spectroscopy at an accuracy of 0.008 cm−1. Transitions to upper states belonging to several ns and nd Rydberg series that converge to the 4S3/2, 2D, and 2P ionization limits are presented. Besides studies on the main 16O isotope, measurements of the 18O isotope are also performed, for which an enriched sample of 18O2 gas is used. A least-squares optimization analysis is performed after merging the present new data set with some relevant accurate literature data to extract a list of level energies at high accuracy. When comparing with the database of the National Institute of Standards and Technology, good agreement is found for levels with low principal quantum numbers n ≤ 7 or below excitation energies of 108,000 cm−1; however, significant deviations were found for levels with n > 7. The main result of the present study is the realization of an improved data set of transition frequencies and level energies for O i, with its usefulness demonstrated in a comparison with high-resolution astronomical spectra showing absorption in the line of sight to distant quasars.

The parallel-plate compression test is one of the simplest ways to measure the mechanical properties of a material. In this test, the Young’s modulus ( E ) and the Poisson’s ratio ( ν ) of the material are determined directly without applying any additional modelling and parameter fitting in the post-processing. This is, however, limited when dealing soft biological materials due to their inherent properties such as being inhomogeneous, microscopic, and overly compliant. By combining an interferometry-assisted parallel-plate compression system and a confocal microscope, we were able to overcome these limitations and measure the E (315 ± 52 Pa) and ν (0.210 ± 0.043) of fixated and permeabilized bovine oocytes.