Abstract View
Vibrational Modes of 2-Methyltetrol Sulfates from Raman and Infrared Spectroscopy
ALISON FANKHAUSER, Ziying Lei, Kimberly Daley, Yao Xiao, Andrew Ault, University of Michigan
Abstract Number: 502
Working Group: Aerosol Chemistry
Abstract
Vibrational modes of the isoprene oxidation product 2-methyltetrol sulfates (2MTS) were spectroscopically probed using Raman and infrared (IR) spectroscopies, supported with density functional theory. Experimental Raman and attenuated total reflectance-Fourier transform IR spectra collected for aqueous 2MTS at pH 3 agreed with the calculated deprotonated 2MTS spectra better than those of protonated 2MTS. Vibrational modes identified for ν(RO-SO3-) include Raman- and IR-active 1035 cm-1 and 1059 cm-1 as well as IR-active 1192 cm-1 and 1237 cm-1. Comparing the Raman spectra for 2MTS across a range of acidities (pH = 0 – 10) suggest that organosulfates will be in their deprotonated form in atmospheric particles. Markers identified for RO-SO3- were in good agreement amongst various IR techniques, including first of its kind optical-photothermal infrared (O-PTIR) and atomic force microscopy-PTIR spectroscopies, and can be used to analyze future chamber and field data for the presence of 2MTS.