For a detailed description of the TLS instrument in SAM, the reader is 
referred to P. R. Mahaffy et al., "The Sample Analysis at Mars Investigation 
and Instrument Suite", Space Sci. Rev. 170, 401-478 (2012). For detailed 
description of the spectral scans, line identification, data processing and 
calibration, the reader is referred to the manuscripts and Supplementary 
Online Material (SOM) accompanying four Science papers: 
(i) C.R. Webster et al., "Isotope Ratios of H, C and O in CO2 and H2O of the 
Martian Atmosphere", Science 341, 260 (2013); 
(ii) C.R. Webster et al., "Low Upper Limit to Methane Abundance on Mars", 
Science 342, 355 (2013); and
(iii) C.R. Webster et al. "Mars methane detection and variability at Gale crater."
Science 347.6220 (2015): 415-417. 
(iv) C.R. Webster et al. "Background levels of methane in Mars atmosphere show strong seasonal variations", Science 360, 1093-1096 (2018).
These four papers focus on atmospheric data and results. 
For the Evolved Gas Analysis (EGA) runs, further details are given in a fifth Science paper authored by Laurie Leshin et al., namely:
(v)  L.A. Leshin et al., "Volatile, Isotope, and Organic Analysis of Martian Fines with the Mars Curiosity Rover", Science 341, (2013); DOI 10.1126/science.1238937.

For the enriched methane run, atmospheric gas is led in across a carbon 
dioxide scrubber (that removes much of the carbon dioxide and not methane) 
until the Herriott cell pressure reaches atmospheric pressure (nominal 7 mbar) 
or until 2 hours have passed, whichever comes first. Then 
scans across the methane region are made according to the usual script 
described in the published paper on low methane abundance. The enrichment 
script was fully tested in the SAM test bed at GSFC to produce an enrichment 
factor of about 25. Provided data has this division already made to reflect 
the original Mars methane abundance with its correspondingly lower uncertainty.
All methane values given have been corrected to global annual mean mixing ratios.
Briefly, for EGA analysis, ingested solid sample is heated in a pyrolysis 
oven whose gaseous products are routed to either QMS, TLS or GC in a helium 
gas flow.  For any EGA run, TLS is given a "temperature cut" where the 
effluent is delivered to the TLS Herriott cell during a certain oven 
temperature portion of its heating ramp, typically a 50-100 deg C cut that 
may be at lower or higher temperature, and identified in our level 2 data set.
Isotopic ratios for d17O and d13C18O, while provided for standard 
"atmospheric" runs, cannot retrieve meaningful values for EGA runs where 
spectral signals (line depths) are much weaker. 
Rocknest EGA effluent gases were observed by the QMS to contain contamination 
from a derivatization agent MTBSTFA that was taken along with the SAM 
experiment.  For TLS, numerous underlying spectral lines were observed in 
our spectral scans whose contribution to the CO2 and H2O isotopic lines 
could not be unambiguously identified.  However, these interferences were 
generally small, and diminished throughout the Rocknest run series, made 
only minor contributions to the John Klein and Cumberland analyses, and 
were of negligible contribution to all subsequent EGA runs.
For EGA analysis, it is important to take into account what gases and 
isotope ratios would result with NO sample in the pyrolysis oven.  To that 
end, the EGA run is duplicated in this condition (no sample) and minor 
amounts of both CO2 and H2O are produced and detected in TLS.  Because 
these "blank cup" gases are measured by TLS to have isotopic ratios 
different from the Mars solid samples, we have made corrections to the 
level 2 data based on a blank cup analysis usually run immediately before 
each series (Rocknest, John Klein, Cumberland). These corrections are 
described in the Leshin et al. Science paper referenced above.  Small 
corrections due to laser line position have also been applied. 
For the combustion experiments, TLS receives gas in 3 steps after the oven 
is held at a constant temperature and oxygen added for combustion of organic 
compounds into CO2, and removal of low temperature components from the TLS 
prior to introduction of gas released at higher temperatures. The steps 
involve sampling first at low temperatures, then heating to 550 deg C for 
one sample, then to 950 deg C for the final sample.
Isotope ratios given refer to SMOW for oxygen isotopes and VPDB for d13C 
ratios. These ratios were determined using identical data processing software 
in comparison to certified calibration gas or liquid standards determined by 
IRMS (see published SOM). All isotope delta values and their standard errors 
(one-sigma, SE) are given in "per mil" according to standard convention. In 
some cases (entries marked with "x") scientifically useful data was not 
retrieved due to instrumentation issues such as fast moving spectral scans or 
poor signal-to-noise ratios. In atmospheric cases, values for d13C and d18O 
result from the mean value from the two spectral regions 1 and 2 accessed 
by a single laser by changing the laser temperature, but in the EGA results, 
we use line-pairs that appear better behaved with respect to contaminant or 
underlying spectral line issues. We emphasize that the understanding and 
analysis of identified and unidentified contaminants and underlying spectral 
lines is ongoing, and will result in future corrections (updates) to our 
level 2 data.
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