DESIGN AND APPLICATIONS OF A MASS-CORRELATED BROADBAND MICROWAVE SPECTROMETER

Chirped pulse Fourier transform microwave (CP-FTMW) spectroscopy serves as a faster-than-ever technique for structure determination that is being utilized in an ever-widening range of applications. Vacuum ultraviolet (VUV) time-of-flight mass spectrometry (TOFMS) provides a gentle and general ionization scheme for measurement of the masses, and hence molecular formulae, of the components of a gas mixture, as long as these components have ionization potentials below the threshold for single-photon photoionization (118 nm = 10.5 eV in this case). By combining these two methods, a powerful tool is created for determining the structures of the components in a mixture. By following the correlation between the microwave transition intensities and the mass-resolved signals in the TOF mass spectrum, the molecular formulae of the carriers of the microwave transitions can be determined. In this sense, the combination of CP-FTMW with VUV TOFMS produces mass-correlated broadband microwave spectra. Herein, we discuss the design, construction and initial applications of a new chamber that was designed to acquire simultaneous mass and rotational spectra. Proof of concept will be demonstrated by examining a gaseous mixture of 2-methoxyfuran, furan and furfural. The new spectrometer is also being used to characterize resonance stabilized radicals formed by a pyrolysis source. Application in this context will also be discussed