Transient absorption spectroscopy on spiropyran monolayers using nanosecond pump-probe Brewster angle reflectometry

Bernhard Siebenhofer, Sergey Gorelik, Martin J. Lear, Hong Yan Song, Christoph Nowak, Jonathan Hobley

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Self-assembled monolayers of 11-(3′,3′-dimethyl-6,8- dinitrospiro[chromene-2,2′-indoline]-1′-yl) undecanoic acid (amphiphilic spiropyran) at the air-water interface are studied using Brewster angle reflectometry. Transient kinetics of the spiropyran to merocyanine conversion are recorded in a UV-pump, VIS-probe configuration. By varying the probe wavelength using an optical parametric oscillator, we are able to reconstruct absorption spectra of intermediate states with a time-resolution of 10 nanoseconds, limited by the temporal convolution of the two laser pulses. After UV irradiation, spiropyran converts to merocyanine in two stages. The first occurs within a timescale of several tens of nanoseconds and is heavily convoluted with the system response time, whereas the second stage occurs over a few hundred nanoseconds. During the rise time there is a small red shift in the transient absorption spectrum of ∼20 nm. We assign the red shift and the slower kinetics to the isomerization of a merocyanine isomer cis about the central methine bond to those that are trans about the same bond.

Original languageEnglish
Pages (from-to)848-853
Number of pages6
JournalPhotochemical and Photobiological Sciences
Volume12
Issue number5
DOIs
Publication statusPublished - 2013

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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