Molecular Photophysics

Due to the low rate of spontaneous emission, a number of processes appear before emission. The processes depend strongly on the molecule therefore, the content of the next section is referred to as molecular photophysics. 

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Birks, J. Organic Molecular Photophysics Wiley New York, 1975. 

Birks J. B. (Ed.) (1975) Organic Molecular Photophysics, Vols. 1 and 2, John Wiley Sons, London. 

Labhart, H., Heinzelmann, W. Triplet-triplet absorption spectra of organic molecules. In Organic molecular photophysics. Vol. l,p.297. (ed. J. B. Birks). New York Wiley 1973. 

Molecular Photophysics of Acridine Yellow Studied by Phosphorescence and Delayed Fluorescence 188... 

J. B. Birks (Ed.), Organic Molecular Photophysics, Vol. 1, Wiley, London, 1973. J.B. Birks (Ed.), Organic Molecular Photophysics, Vol. 2, Wiley, London, 1975. 

G. Beddard, Molecular Photophysics, Repts. Prog. Phys. 56, 63 (1993). 

Birks JB (1970) Organic molecular photophysics. Wiley, New York, p 545... 

Within the context of supramolecular devices, re-emission of the radiation by luminescence is of interest in sensing and signalling applications, while chemical reactions are of interest in applications such as molecular switches and photocatalysis. Strictly speaking absorption and re-emission type processes are termed molecular photophysics while light-induced chemical reactions or chemical processes are termed photochemistry . 

Wilkinson, F. In Organic Molecular Photophysics, Editor, Birks, J.B. John Wiley and Sons 1975, Vol. 2 p. 95. 

Thiophosgene is one of the simplest and best-studied prototype systems for which accurate potential energy surfaces can be obtained through experiment and high-level ab initio calculations. As such, thiophosgene is a molecule tailor-made for the fundamental understanding of electronic relaxation in polyatomic molecules. The results summarized in this chapter confirm the special role thiophosgene plays in the field of molecular photophysics and photochemistry. 

In conjugated polymers and oligomers, the behavior of photoexcited states obeys general rules of molecular photophysics, such as the Kasha [88] and Vavilov [77] rules. These are empirical observations, rather than exact statements or laws. However, they provide a useful basis for discussion. The Kasha rule states that fluorescence occurs from the lower-lying excited state, independently of the excitation energy. The Vavilov rule states that the fluo-... 

Understandably, there is an enormous richness in the photophysical and photochemical behavior of the excited states present in diimine rhenium tricarbonyl complexes. Indeed, this plethora of molecular photophysical characteristics has led to a wide range of interesting and important applications, including their use as catalysts [21-25], sensors [26-33], probes for photo-polymerization [10, 34, 35], optical switches [36 15], light-emitting materials [46-52], nonlinear optical materials [53-56], binding or photocleavage of DNA [57-61], and radiopharmaceuticals [62-66], Under the purview of this article our focus will be to cover photophysical and photochemical properties and hence other aspects, such as synthetic, catalytic, pharmaceutical, etc., will not be discussed. 

Lim EC (1986) Proximity effect in molecular photophysics Dynamical consequences of pseudo-Jahn-Teller interaction. Journal of Physical Chemistry 90 6770-6777. 

Klopffer W (1973) Intramolecular Excimers. In Birks JB (ed) Organic Molecular Photophysics, Interscience, London, p 35. 

Beens H, Weller A (1975) In Birks JD (ed) Organic molecular photophysics. Wiley, London, vol 2, chapter 4 Mataga N, Ottolenghi M (1975) In Foster R (ed) Molecular association. Academic, London, vol 2, chap 1... 

Understanding the field enhancement of radiative rates is insufficient to predict how molecular photophysical properties such as enhancement of fluorescence quantum yield will be affected by interactions of the molecule with plasmons. A more detailed model of the photophysics that accounts for non-radiative rates is necessary to deduce effects on photoluminescence (PL) yields. Such a model must include decay pathways present in the absence of metal nanoparticles as well as additional pathtvays such as charge transfer quenching that are associated with the introduction of the metal particles. Schematically, we depict the simplest conceivable model in Figure 19. IB. Note that both the contributions of radiative rate enhancement and the excited state quenching by proximity to the metal surface will depend on distance of the chromophore from the metal assembly. In most circumstances, one expects the optimal distance of the chromophores from the surface to be dictated by the competition between quenching when it is too close and reduction of enhancement when it is too far. The amount of PL will be increased both due to absorption enhancement and emissive rate enhancement. Hence, it is possible to increase PL substantially even for molecules with 100 % fluorescence yield in the absence of metal nanoparticles. 

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