KOALA: A program for the processing and decomposition of transient spectra

Michael P. Grubb*, Andrew J. Orr-Ewing, Michael N. R. Ashfold

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

50 Citations (Scopus)
565 Downloads (Pure)


Extracting meaningful kinetic traces from time-resolved absorption spectra is a non-trivial task, particularly for solution phase spectra where solvent interactions can substantially broaden and shift the transition frequencies. Typically, each spectrum is composed of signal from a number of molecular species (e. g., excited states, intermediate complexes, product species) with overlapping spectral features. Additionally, the profiles of these spectral features may evolve in time (i.e., signal nonlinearity), further complicating the decomposition process. Here, we present a new program for decomposing mixed transient spectra into their individual component spectra and extracting the corresponding kinetic traces: KOALA (Kinetics Observed After Light Absorption). The software combines spectral target analysis with brute-force linear least squares fitting, which is computationally efficient because of the small nonlinear parameter space of most spectral features. Within, we demonstrate the application of KOALA to two sets of experimental transient absorption spectra with multiple mixed spectral components. Although designed for decomposing solution-phase transient absorption data, KOALA may in principle be applied to any time-evolving spectra with multiple components. (C) 2014 AIP Publishing LLC.

Original languageEnglish
Article number064104
Number of pages7
JournalReview of Scientific Instruments
Issue number6
Early online date26 Jun 2014
Publication statusPublished - Jun 2014




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