The transient absorption of 1,3,5-tri-tert-butyl-pentalene
Year: 2001
Authors: Bussotti L., Foggi P., Gellini C., Moroni L., Salvi P.R.
Autors Affiliation: Laboratorio di Spettroscopia Molec., Dipartimento di Chimica, Università di Firenze, Via Gino Capponi 9, 50121 Firenze, Italy
Abstract: The transient absorption of 1,3,5-tri-tert-butyl-pentalene in cyclohexane solution has been measured at room temperature exciting at 340 nm with femtosecond pulses. Two relaxation processes have been determined, the first, very rapid, with time constant 650 fs and the second, occurring on a picosecond timescale, with estimated decay time 13 ps. The former is due to the vibronic relaxation from upper S3 levels to the S3 minimum, the latter to the decay from S3 to S0. This interpretation is in good agreement with results of ab initio calculations on pentalene and its alkyl derivatives, 1,3,5-tri-ethyl, 1,3,5-tri-sec-propyl and 1,3,5-tri-tert-butyl. MCSCF/CAS calculations, perturbatively corrected within the scheme of quasi-degenerate perturbation theory (QDPT), of vertical S0 ? Sn excitation energies allow us to study the dependence of excitation energies on substitution. Calculated S3 ? Sn and S4 ? Sn absorption spectra of pentalene at the S0, S3 and S4 equilibrium geometries that vibronic levels of S3 rather than of S4 are excited by the strong pump pulse with subsequent decay within this state.
Journal/Review: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Volume: 3 (15) Pages from: 3027 to: 3033
KeyWords: 1,3,5 tri tert butylpentalene; alkene derivative; cyclohexane; unclassified drug, absorption spectroscopy; article; calculation; chemical structure; energy; excitation; geometry; mathematical model; measurement; pump; temperature; theory; timeDOI: 10.1039/b103114gImpactFactor: 1.787Citations: 8data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-11-10References taken from IsiWeb of Knowledge: (subscribers only)Connecting to view paper tab on IsiWeb: Click hereConnecting to view citations from IsiWeb: Click here
