Publications by authors named "Parker B Crandall"

2 Publications

  • Page 1 of 1

Untangling the formation and liberation of water in the lunar regolith.

Proc Natl Acad Sci U S A 2019 06 20;116(23):11165-11170. Epub 2019 May 20.

Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822;

The source of water (HO) and hydroxyl radicals (OH), identified on the lunar surface, represents a fundamental, unsolved puzzle. The interaction of solar-wind protons with silicates and oxides has been proposed as a key mechanism, but laboratory experiments yield conflicting results that suggest that proton implantation alone is insufficient to generate and liberate water. Here, we demonstrate in laboratory simulation experiments combined with imaging studies that water can be efficiently generated and released through rapid energetic heating like micrometeorite impacts into anhydrous silicates implanted with solar-wind protons. These synergistic effects of solar-wind protons and micrometeorites liberate water at mineral temperatures from 10 to 300 K via vesicles, thus providing evidence of a key mechanism to synthesize water in silicates and advancing our understanding on the origin of water as detected on the Moon and other airless bodies in our solar system such as Mercury and asteroids.
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June 2019

Accessing the Nitromethane (CHNO) Potential Energy Surface in Methanol (CHOH)-Nitrogen Monoxide (NO) Ices Exposed to Ionizing Radiation: An FTIR and PI-ReTOF-MS Investigation.

J Phys Chem A 2018 Mar 23;122(9):2329-2343. Epub 2018 Feb 23.

Department of Chemistry , University of Hawai'i at Ma̅noa , Honolulu , Hawaii 96822 , United States.

(D-)Methanol-nitrogen monoxide (CHOH/CDOH-NO) ices were exposed to ionizing radiation to facilitate the eventual determination of the CHNO potential energy surface (PES) in the condensed phase. Reaction intermediates and products were monitored via infrared spectroscopy (FTIR) and photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) during the irradiation and temperature controlled desorption (TPD) phase, respectively. Distinct photoionization energies were utilized to discriminate the isomer(s) formed in these processes. The primary methanol radiolysis products were the methoxy (CHO) and hydroxymethyl (CHOH) radicals along with atomic hydrogen. The former was found to react barrierlessly with nitrogen monoxide resulting in the formation of cis- and trans-methyl nitrite (CHONO), which is the most abundant product that can be observed in the irradiated samples. On the other hand, the self-recombination of hydroxymethyl radicals yielding ethylene glycol (HO(CH)OH) and glycerol (HOCHCH(OH)CHOH) is preferred over the recombination with nitrogen monoxide to nitrosomethanol (HOCHNO).
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March 2018