Acquisition of Raman spectra of amino acids using portable instruments: Outdoor measurements and comparison

Raman spectra of 13 amino acids: l-alanine, β-alanine, l-asparagine, l-aspartic acid, l-glutamic acid, l-glutamine, glycine, l-methionine, l-proline, l-serine, l-threonine, l-tryptophan and l-tyrosine were acquired outdoors using two portable Raman instruments from the Ahura and Delta Nu manufacturers, both with 785 nm laser excitation. Both instruments provide quality Raman spectra with nevertheless a variable dependence upon the prevailing experimental conditions. The data acquired in these experiments will inform the selection of suitable Raman spectrometers for the in-field detection of biomolecules of relevance to the search for life signatures spectroscopically in terrestrial extreme environments and in extraterrestrial exploration, especially of planetary surfaces and subsurfaces using robotic instrumentation.