How important is roaming in the photodegradation of nitrobenzene?. Issue 28 (23rd June 2020)

• Record Type: Journal Article
• Authors: Giussani, Angelo; Worth, Graham A.
• Is Part Of: Physical chemistry chemical physics. Volume 22:Issue 28(2020)
• Page Start: 15945
• Page End: 15952
• Publication Date: 2020-06-23
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d0cp02077j
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Three pathways have been found for the formation of NO from nitrobenzene photodegradation that lead to either low or high translational energy, with a roaming mechanism involved at high excitation energies. Abstract : At low excitation energies nitrobenzene photoreleases NO with low translational and rotational energy, while at higher excitation energies NO is photoreleased with both low and high translational and rotational energy. The fast products are formed through a singlet–triplet crossing (STC) region featuring an oxaziridine ring, while a ground state roaming mechanism was suggested to produce the slow molecules. Computing translational and rotational energies performing CASSCF classical dynamics, we here prove how the same oxaziridine STC can account for both fast and slow photoproducts, depending on the region of the seam through which the ground state is populated. A roaming-type STC/CI has also been characterized, from which slow NO molecules can also be formed through a roaming photodegradation mechanism, here in the excited state. The higher accessibility of the oxaziridine STC mechanism, 1.53 eV lower in energy than the roaming path, questions the contribution of roaming in nitrobenzene NO photoproduction.