The broadband rotational spectrum of fully deuterated acetaldehyde (CD3CDO) in a CW supersonic expansion

Abstract The broadband pure rotational spectra of CD 3 CDO, 13 CD 3 CDO, CD 3 13 CDO, and CD 3 CD 18 O have been recorded using a BrightSpec W-Band (75–110 GHz) chirped-pulse Fourier transform millimeter wave (CP-FTmmW) spectrometer. The sample was enriched with deuterium, whereas the 13 C and 18 O isotopologues were observed in natural abundance (with respect to the enriched fully deuterated parent containing 12 C and 16 O). The analysis of the spectra is described and the derived molecular constants are compared to those of known acetaldehyde isotopologues. Furthermore, we have demonstrated the ability to record rotational spectra in a steady-state “CW” supersonic expansion with a duty cycle of 80%. The advantages and limitations of the segmented chirp spectrometer coupled with a CW molecular source as well as design of the vacuum and pumping system are discussed.