Excited molecules pathways taken

There are other possible pathways that may be taken by the excited molecule XY in Reaction (7.7). These can be represented by... 

Atomic cryocrystals which are widely used as inert matrices in the matrix isolated spectroscopy become non-inert after excitation of an electronic subsystem. Local elastic and inelastic lattice deformation around trapped electronic excitations, population of antibonding electronic states during relaxation of the molecular-like centers, and excitation of the Rydberg states of guest species are the moving force of Frenkel-pairs formation in the bulk and desorption of atoms and molecules from the surface of the condensed rare gases. Even a tiny probability of exciton or electron-hole pair creation in the multiphoton processes under, e.g., laser irradiation has to be taken into account as it may considerably alter the energy relaxation pathways. 

The funnel approach restricts the number of the possible pathways. Kinematically, it means that for n local rotations — no matter which path down the funnel has been taken by the molecule — there appears the constraint of small n. This constraint comes from the spectroscopic data on the poorly dimensionally sensitive dispersion laws of the internal quasiparticle excitations [9,10], which stem the same order of magnitude for the two time intervals, for the molecular conformational transition (t), as well as for the (average) time of the local segmental rotations (t,), while bearing t = otj in mind. Certainly, this might be a serious restriction, in principle, for the large molecules conformational transitions in the still (semi-)classical funnel approach. 

Quantum-mechanical ab initio calculations for small molecular systems are widely used these days as an instrument in studying problems in various Helds of chemistry and molecular physics . Most studies deal with ground-state phenomena, i.e. the structure and properties of compounds, thermal reaction pathways and dynamical behavior based on this information. There has been a noticeable increase in excited-state studies in recent years, however, in particular in connection with problems in molecular spectroscopy, in ionization processes or in the detailed study of photochemical reactions, such as photodissociation, energy-transfer and charge-exchange reactions. The calculations are especially powerful for small molecules (for example, for systems up to SO electrons and six atoms other than hydrogen), and hence numerous applications are found in particular in the area of atmospheric and interstellar chemistry and in the study of combustion processes. In these Helds it is often found that experimental and theoretical studies are undertaken in close conjunction and that the two yield complementary data which, taken together, are able to clarify a process. In other instances it is not uncommon that for short-lived species the values obtained from calculations are so far the only ones available. 

To put it differently, besides activation of Ns molecules by means of light absorption, in deaerated PMMA films an additional quite effective pathway of excitation, associated with radiationless T-T transmission of energy from incapacious nanopores to supemanopores, acts. The reaction model discussed for CTA samples does not take into accoimt transmission of electron excitation energy in this direction however, in general case, based on the results [13], such possibility should be taken into accoimt. 

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