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An E-Band (60–90 GHz) chirped-pulse Fourier transform millimeter-wave spectrometer has been constructed for eventual kinetics and dynamics studies. The performance of the spectrometer is demonstrated with the molecule nitroxyl (HNO). Using the new spectrometer and by passing isotopically labelled methyl nitrite (CH 3 ONO) through a pyrolysis nozzle, the spectra of minor isotopologues of HNO have been obtained. The observations on the isotopologues identified here, H 15 NO, HN 18 O, and D 15 NO, have been combined with the earlier isotopic observations, HNO and DNO, to create a global r m ( 1 ) HNO geometry that approximates an equilibrium structure. The results are compared to high-level ab initio calculations. [ABSTRACT FROM AUTHOR]

This second paper in a series of two reports on the performance of a new instrument for studying chemical reaction dynamics and kinetics at low temperatures. Our approach employs chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy to probe photolysis and bimolecular reaction products that are thermalized in pulsed uniform flows. Here we detail the development and testing of a new Ka-band CP-FTMW spectrometer in combination with the pulsed flow system described in Paper I [J. M. Oldham, C. Abeysekera, B. Joalland, L. N. Zack, K. Prozument, I. R. Sims, G. B. Park, R. W. Field, and A. G. Suits, J. Chem. Phys. 141, 154202 (2014)]. This combination delivers broadband spectra with MHz resolution and allows monitoring, on the /xs timescale, of the appearance of transient reaction products. Two benchmark reactive systems are used to illustrate and characterize the performance of this new apparatus: the photodissociation of SO2 at 193 nm, for which the vibrational populations of the SO product are monitored, and the reaction between CN and C2H2, for which the HCCCN product is detected in its vibrational ground state. The results show that the combination of these two well-matched techniques, which we refer to as chirped-pulse in uniform flow, also provides insight into the vibrational and rotational relaxation kinetics of the nascent reaction products. Future directions are discussed, with an emphasis on exploring the low temperature chemistry of complex polyatomic systems. [ABSTRACT FROM AUTHOR]