Two-photon ionisation

Fig. 16. Comparison between the absorption spectra recorded in liquid ethane-1,2-diol at early time after two-photon ionisation (Fig. 13) at 295 K and the absorption spectra of the solvated electron obtained at high temperature by pulse radiolysis.

Soroushian B, Lampre I, Pernot P, De Waele V, Pommeret S, Mostafavi M. (2004) Formation and geminate recombination of solvated electron upon two-photon ionisation of ethylene glycol. Chem Phys Lett 394 313-317. 

The Si — So Resonant Two-Photon Ionisation Spectrum of Supersonically Cooled Triptycene... 

Figure 9 Transient absorption spectra of excess electrons in liquid ethane-1,2-diol for five time-delays after two-photon ionisation ofthe solvent by 200 fs pulses at 263 nm from [18], The basic features ofthe solvated...

Soroushian B., Lampre I., Bonin J., Pernot R, Pommeret S., Mostafavi M., Solvation dynamics ofthe electron produced by two-photon ionisation of liquid polyols. 1. Ethylene glycol, J. Phys. Chem. A, 2006,110,1705-1717. 

Fig. 9.1. Resonantly enhanced two-photon ionisation in Na. Two lasers are used the sum of the two frequencies is fixed, and the intermediate energy is tuned through the 3p doublet. The inset shows the region close to resonance (after J.E. Bjorkholm and P.F. Liao [466]).

P.M. Radmore, P.L. Knight, Two-photon ionisation Interference and population trapping, Phys. Lett. A 102 (1984) 180. 

A. Herrmann, M. Hofmann, S. Leutwyler, E. Schumacher, and L. Woste, Optical Spectroscopy of Nas by Two-Photon-Ionisation in a Supersonic Molecular Beam , Chem. Phys. Lett. 62, 216 (1979). 

For polymers with a suitable chromophore, such as aromatic groups, two-photon ionisation makes it possible to perform photoionisation at commercial laser wavelengths. This approach provides a certain degree of selectivity of detection. 

Fig. 3.10. L MS applied to polymer/additives (A, B, C). The polymer is irradiated by an IR laser pulse (a) and decomposes and is ejected from the bulk together with intact additives (b). Selective ionisation is carried out by a UV laser with resonant two-photon ionisation (c). The ions are mass separated and recorded in a time-of-flight mass spectrometer. After Zenobi [251]. Reproduced from R. Zenobi, Fresenius J. Anal Chem. 348, 506-509 (1994), by permission of...

The relaxation mechanisms of modified or derivative nucleobases are also very helpful to understand the peculiar photochemical properties of the canonical nucleobases. In 2012, Bakalska and Delchev compared the decay paths of cytosine and isocytosine. In 2013, Engler et focused on the differences between 9H-adenine and 9-acetyladenine by carrying out a study combining data obtained from resonant two-photon ionisation spectroscopy of the laser-desorbed molecules and DFT/MRCI... 

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