Multiphoton absorption probability

However, it is possible to probe such a relativistic dynamics with a second field with a lower frequency, so that multiphoton absorption, leading to ATI, can take place. In order to ionize such a stabilized atom with a significant, probability, the second field must force the electron wave function to explore again the vicinity of the nucleus to be able to absorb energy (i.e. photons). This can he achieved by chosing parallel polarizations and field strength intensities and frequencies such that the characteristic excursion lengths [Pg.114]

The use of lanthanides are common for optical purposes because of their narrow and sharp bands, and distinguishable long lifetimes, accomparied by low transition probabilities due to the forbidden nature of the transitions [10-13]. Thus chromophoric sensitization of ligand to metal has been subjected to numerous theoretical and experimental investigations [14—16]. However, only limited classes of organic-lanthanide complexes have been developed and shown to display nonlinear processes [17-19]. Common nonlinear processes from lanthanide complexes include harmonic generation, photon up-conversion and multiphoton absorption induced emission. 

If the first step of the multiphoton excitation can be chosen isotope selectively so that a wanted isotopomer has a larger absorption probability than the other iso-topomers of the molecular species, selective dissociation may be achieved [270],... 

Of particular interest is the multiphoton dissociation by infrared lasers, which can be studied in more detail by such an arrangement. One example is the dissociation of SOj ions induced by multiphoton absorption of CO2 laser photons. The relative probability for the two channels... 

Nonstatistical unimolecular product energy distributions have been either measured or deduced from infrared multiphoton absorption, molecular beam, arrested infrared chemiluminescence, and gas bulb chemical activation experiments. Except for a few anomalous cases, these nonstatistical distributions probably result from exit-channel coupling effects. These effects are due to potential energy characteristics in the exit-channel and at the present time very little is known about them. It may prove to be possible to classify unimolecular potential energy surfaces by their exit-channel properties. However, the classifications will most likely be considerably more detailed than what has been found for A -f BC AB + C potential energy surfaces,17-19,1315132... 

Photodecomposition of a 4-nitrophenyl moiety is a multiphoton process absorption of one photon leads to the singlet, which relaxes immediately into a long-lived triplet state. Capturing another photon transforms the singlet through a dissociative decay process into reactive intermediates, probably radicals, which react with nucleophilic sites. In the absence of a reactive species, these reactive intermediates will relax into the initial ground state 23 ... 

Two-photon excited fluorescence detection at the single-molecule level has been demonstrated for chromophores in cryogenic solids [M], room-temperature surfaces [61], membranes [62] and liquids [63, M and 65]- Although multiphoton excited fluorescence has been embraced with great enthusiasm as a technique for both ordinary confocal microscopy and single-molecule detection, it is not a panacea in particular, photochemical degradation in multiphoton excitation may be more severe than with ordinary linear excitation, probably due to absorption of more than the desired number of photons from the intense laser pulse (e.g. triplet excited state absorption) [61],... 

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