Photodissociation of Methyl Iodide and Methyl Iodide Clusters at 193 nm

• Published in: Journal of physical chemistry. C Vol. 117; no. 43; pp. 22383 - 22390
• Main Authors: Kartakoullis, Andreas, Samartzis, Peter C, Kitsopoulos, Theofanis N, Parker, David H
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 31-10-2013
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Angular distribution; Methyl compounds; Iodomethane; Photodissociation; Vibrational mode
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp403008z

This study introduces the state resolved dynamics of CH3I when clustered in a supersonic expansion using He and Xe as seeding gases. Following excitation at 193 nm (6.4 eV), state specific alterations in photodissociation dynamics are observed. Four vibrational levels (ν2 = 0, 1, 2, 3) of the CH3 umbrella vibrational mode were probed, as were I(2P3/2) and I(2P1/2) atomic photofragments. For nascent CH3 fragments the measured kinetic energy releases and angular distributions show enormous sensitivity to the clustering. Manifestation of the clustering dynamics include: (a) shifting to higher energies (by up to 0.5 eV) and significant broadening of the kinetic energy distribution; (b) vibrational dependence of this increase in product kinetic energy; (c) angular distribution changes from a characteristic perpendicular character observed in free-standing CH3I into a parallel transition for the clustered moiety. Drastic effects of clustering are also observed when probing iodine-atom photofragments, namely the state resolved distribution observed when seeding in He is replaced by a broad structureless distribution when seeding in Xe.