Browsing by Author "Lo, J-I"

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Qualitative observation of reversible phase change in astrochemical ethanethiol ices using infrared spectroscopy
(2017-05-05)
Pavithraa, S.
;
Methikkalam, R. R. J.
;
Gorai, P.
;
Lo, J-I
;
Das, A.
Here we report the first evidence for a reversible phase change in an ethanethiol ice prepared under astrochemical conditions. InfraRed (IR) spectroscopy was used to monitor the morphology of the ice using the S H stretching vibration, a characteristic vibration of thiol molecules. The deposited sample was able to switch between amorphous and crystalline phases repeatedly under temperature cycles between 10 K and 130 K with subsequent loss of molecules in every phase change. Such an effect is dependent upon the original thickness of the ice. Further work on quantitative analysis is to be carried out in due course whereas here we are reporting the first results obtained. (C) 2017 Elsevier B.V. All rights reserved.
Vacuum ultraviolet photoabsorption of prime ice analogues of Pluto and Charon
(2018-02-05)
Pavithraa, S.
;
Lo, J-I
;
Rahul, K.
;
Sekhar, B. N. Raja
;
Cheng, B-M.
Here we present the first Vacuum UltraViolet (VUV) photoabsorption spectra of ice analogues of Pluto and Charon ice mixtures. For Pluto the ice analogue is an icy mixture containing nitrogen (N-2), carbon monoxide (CO), methane (CH4) and water (H2O) prepared with a 100:1:1:3 ratio, respectively. Photoabsorption of icy mixtures with and without H2O were recorded and no significant changes in the spectra due to presence of H2O were observed. For Charon a VUV photoabsorption spectra of an ice analogue containing ammonia (NH3) and H2O prepared with a 1:1 ratio was recorded, a spectrum of ammonium hydroxide (NH4OH) was also recorded. These spectra may help to interpret the P-Alice data from New Horizons. (C) 2017 Elsevier B.V. All rights reserved.