The temperature effect on the glycine decomposition induced by 2 keV electron bombardment in space analog conditions

Effect of Perchlorates on Electron Radiolysis of Glycine With Application to Mars

“…Alterations in the IR spectra of the pure glycine samples can be induced when irradiated with high-energy electrons during the experiments. This can be verified when comparing the irradiated sample spectra (Figure 1(D)) to the pristine sample (Figure 1(E)) measured at 10 K: keeping the sample at this temperature for 1 hr does not alter its IR spectrum at all, whereas irradiating the sample for the same time causes significant changes in it, which is in complete agreement with the results of previous experimental works (Pilling et al 2014;Maté et al 2014Maté et al , 2015. In general, all features decrease and broaden upon irradiation; the simultaneous degradation, amorphization, and oligomerization (to oligopeptides, (-HN-CH 2 -CO-) n ; Kaiser et al 2013;Pilling et al 2013) of the crystalline organic sample may account for this phenomenon.…”

“…Besides, the calculated half-life times of the amorphous form were similar to the data from experiments carried out with megaelectronvolt protons (Gerakines et al 2012). It is worth noting that these findings contradict the results from Pilling et al (2014). According to their results, the dissociation cross section of crystalline glycine is inversely proportional to the temperature; that is, glycine decomposes five times faster at 14 K than at 300 K. Furthermore, half-life times of the α and β forms were found to be at least an order of magnitude longer than the half-life times determined by competing groups.…”

“…The best examples for this broadening are the bands between 3250-2400 cm −1 and 1700-1250 cm −1 occurring principally at 260 K (Figure 1(A)). Apart from the ubiquitous decrease of absorption peaks, only one new intense emerging signal can be detected in all experiments at 2340 cm −1 , which belongs to the stretching vibration of CO 2 (ν as CO 2 ), a common decarboxylation product of amino acids when irradiated, as identified by numerous works previously as well (Gerakines et al 2012;Gerakines & Hudson 2013;Pilling et al 2014;Maté et al 2014Maté et al , 2015. However, there is significant evidence of other irradiation products in the spectra that can be responsible for the widening of the peaks (Section 4.2).…”

“…Aside from the ubiquitous decrease of absorption peaks, a new emerging signal can be detected at 2340 cm −1 . As could also be deduced from the experiments with pure glycine, this belongs to the antisymmetric stretching vibration of the common amino acid decarboxylation product of the CO 2 (ν as CO 2 ) molecule (Gerakines et al 2012;Gerakines & Hudson 2013;Pilling et al 2014;Maté et al 2014Maté et al , 2015. The formation of small amounts of carbon monoxide (CO) can also be observed upon irradiation at 10 K; its signal lies at 2131 cm −1 , which can be assigned to its stretching vibration (ν CO).…”

Valine Radiolysis by H+, He+, N+, and S15+ MeV Ions

“…Pilling et al irradiated glycine with 1 MeV H + in order to study the stability of different polymorph configurations [17]. Pilling et al [18], Maté et al [19], and Souza-Corrêa et al [20] studied its dissociation by keV electrons. UV radiolysis was performed by Peeters et al [21] and by Ferreira-Rodrigues et al [22].…”