Ka BAND MICROWAVE SPECTRUM OF METHYL TERT-BUTYL ETHER

Abstract

Methyl tert-butyl ether is a gasoline additive and a water pollutant. Its rotational spectrum was measured from 26.5 -40 GHz using Chirped-Pulse Fourier Transform Microwave Spectroscopy. Measurements were conducted at low temperature via supersonic expansion with two different backing pressures as well as room temperature via static cell. The two different backing pressures provided spectra at ∼ 30 K and ∼ 40 K which allowed meaningful probing of the first excited vibrational state which lies below the first excited torsional state. The room temperature spectrum is highly congested due to low lying vibrational states as well as the torsionally excited states. The molecule was previous reported in Suenram et. al 1997 in a range of 9 -18.6 GHz which fit 32 lines up to J = 3. This work expands that fit to over 400 transitions and converts it to the Rho Axis Method utilizing the program RAM36. The improved ground torsional state measurements as well as the room temperature data allowed for tentative assignments of torsionally excited and vibrationally excited transitions.