TJ02 3-D SUBMILLIMETER SPECTROSCOPY OF ASTRONOMICAL `WEEDS‘ - EXPERIMENTAL AND THEORETICAL ASPECTS OF DATA PROCESSING AND CATALOGING –> TJ03 Ivan R. Medvedev, Sarah M. Fortman, Christopher F. Neese, and Frank C. De Lucia

Class 1 Weeds 1) Methanol – CH 3 OH Methyl Formate – HCOOCH 3 Dimethyl Ether – CH 3 OCH 3 Ethyl Cyanide – CH 3 CH 2 CN Class 2 Weeds 1) Vinyl Cyanide – C 2 H 3 CN Sulfur Dioxide – SO 2 Methyl Cyanide – CH 3 CN Acetaldehyde – CH 3 CHO Astronomical ‘Weeds’ 1) REPORT FROM THE WORKSHOP ON LABORATORY SPECTROSCOPY IN SUPPORT OF HERSCHEL, SOFIA, AND ALMA Pasadena, California October 19 and 20, 2006 Ethyl Cyanide Methanol

Record spectra in the temperature range K Pressure ~ 1-5 mtorr (near Doppler limited line shape) Record spectra in the FASSST mode with post detection bandwidth adequate for detecting a near ‘natural’ line shape Numerically subtract baseline Divide the spectrum by the baseline signal Take natural logarithm of the resulting data to get naperian absorbance (Beer–Lambert law) Experimental

GHz - Heterodyne system TE11 A SUBMILLIMETER CHEMICAL SENSOR. Optics Letters, 35, 10, 1533 (2010)

Spectroscopic Temperature Determination Same for every transition Line Strength - S Identify a set of ‘good’ (unperturbed, not blended, not saturated) previously assigned transitions – ‘reference’ lines Fit experimental intensities of the reference lines to the cataloged values to obtain spectroscopic temperatures and number density for every temperature scan Line Shape Function

Pressure Broadening 1%

Scale Absorbance spectra for each temperature by the corresponding nL/Q parameter Normalizing Spectral Intensities

1. Fitting of the peak intensities for Line Strength and Lower State Energy 2. Point by point fitting of every frequency slice of the spectral data Data reduction strategies 1 2

Fitting of the peak intensities 1.Identifiable blends are fitted to multiple Gaussians 2.Peak absorbance of each line is then fitted to the theoretical model to obtain line strength and lower state energy

Point by point fitting 1.This is an exact expression for an unblended Doppler limited spectral line 2.On line center the point by point and Peak fitting give the same result

Comparison with catalog and experimental data

Comparison of the Point by Point fitting to the experiment and catalogs

Catalogs Fitting of the peak intensities Point by point fitting, Experimental data ApJ, 714, 476 Online Supplementary Materials

Conclusions 3D temperature resolved spectroscopic technique provides experimental and numerical tools for measuring line strengths and lower state energies of every spectral transition without spectroscopic assignment Latest enhancements of the numerical algorithms address the effects of pressure broadening and spectral overlaps Data is cataloged as Frequency, Strength and Lower State Energy at Point by point fitting parameters provide means to predict entire spectra at a user specified temperature. They are cataloged as online supplementary materials of the Astrophysical Journal (ApJ ).