TINo: A thermally insulating nozzle to access elusive molecular libraries for jet-cooled spectroscopy

Molecular jet expansions are critical for producing cold molecular beams for gas-phase molecular spectroscopy. Notably, most of the operating instruments in this class of experiments rely on pulsed valves with intrinsic temperature limits that significantly constrain the efficient vaporization of less volatile compounds. Here, we present and benchmark the Thermally Insulating Nozzle (TINo), a new pulsed nozzle design that supports substantially higher vaporization temperatures without compromising valve integrity. As a proof of concept, we integrated TINo into a chirped-pulse Fourier transform microwave spectrometer and recorded the rotational spectrum of 1,8-naphthalimide, a molecule of interest with a melting point of 300 °C. The enhanced signal-to-noise ratio enabled the detection of both the parent species and the singly substituted 13C isotopologues in natural abundance. TINo opens a viable path toward acquiring laboratory spectra of otherwise inaccessible molecular libraries via jet-cooled molecular spectroscopy.