Lifetime shortening

Kasatani K, Kawasaki M, Sato H (1984) Lifetime shortening of the photoisomer of a cyanine dye by inclusion in a cyclodextrin cavity as revealed by transient absorption spectroscopy. J Phys Chem 88 5451-5453... 

After exclusion of a predissociation process responsible for the lifetime shortening in complexes of benzene with noble gases, we consider the external heavy-atom effect on the intersystems crossing rate as the origin of the lifetime shortening [42]. The strong decrease of the lifetime in the... 

In conclusion, we have found that the intramolecular dynamics in the benzene molecule at low excess energy is not strongly influenced by the additional three vibrational degrees of freedom of the benzene-Ar complex. The coupling of the excited intramolecular modes to the low-frequency inter-molecular modes is weak. The observed 40% decrease of the lifetime of the 61 state does not depend on the individual excited rotation and points to an external heavy-atom effect as the source of the lifetime shortening observed for the same selectively excited rovibronic state. 

The metastablity of antiprotonic helium is known to be affected when foreign atoms and molecules are added to the helium media, as revealed from delayed annihilation time spectra (DATS) in the early stage [2,24,25], However, DATS alone is a macroscopic quantity in which all the microscopic informations cannot be differentiated. Laser resonance techniques have made it possible to investigate microscopically the (n, /[-dependent lifetime shortening effects on the surrounding physico-chemical conditions of antiprotonic helium. 

Ethanol Oligomers in Solution Spectral Holes and Vibrational Lifetime Shortening... 

The simple model of Fig. lb is not expected to reproduce the experimental results of (6) and (7) quantitatively, but it does yield three distinctive and robust features that characterize our model in a relatively large range of system parameters. These include an independence of bridge length for long molecular bridges, an asymmetry that increases as donor lifetime shortens (within physically... 

This effect (not seen up to now) can be explained as follows The brush represents a much lower (5 times) electron density than the silica body nevertheless the potential step vacuum-brash is sufficiently high (more than kT) to be a trap for positronium, and o-Ps is confined in the empty part. The radius of this part is smaller, but Ps wavefunction penetrates a thick brash layer only, and depending on electron density (see Eq.(3)), is much smaller than in pure silica, so the lifetime increases. If the potential step at vacuum-brash boundary is small the penetration range 1/x increases, but the alkane layer is sufficiently thick to prevent Ps reaching silica. Removal of the hydrocarbon phase increases the radius, but increases too, giving as a result lifetime shortening. 

For covalently-bound anthracene in H O the degree of naphthalene lifetime shortening is very sensitive to pH (see Table 7). While X changes only very slightly ° as the pH is lowered from 10.2 to 9.1 the average lifetime of the naphthalene decreases dramatically. This implies a dramatic change in the local structure in the hydrophobic portion of the coll which is only weakly reflected in the changes of the hydrodynamic diameter of the coll (see Table 1). 

Gersten and Nitzan" " developed the theory of lifetimes and quantum yields near metal spheroids. They showed that at short distances the expected change in lifetimes should be larger than near a flat surface by several orders of magnitude, when in resonance with the plasmon of the spheroid. When out of resonance, the effect is limited to a factor of about 10. Thus a total of lifetime shortening of about 10 is expected. 

Despite man s best efforts, many objects have their lifetimes shortened by corrosion.84 The corrosion of metals is an electrochemical process ... 

Because the temperature dependences of these two rate constants are quite close, the atmospheric oxidation rate of CH4 can be scaled to that of CH CCl,. An atmospheric CH4 destruction rate of 440 50 Tg yr can be inferred in this way. From the current atmospheric loading of CH4 of about 4850 Tg, a mean atmospheric lifetime of 11 ( 10%) years is derived based solely on OH reaction. When loss in the stratosphere and removal in soils are also considered, the lifetime shortens to about 10 years. 

However, as mentioned above simple lifetime shortening cannot be responsible for the wide lines seen in other molecules. For example, in many fluorescent molecules the observed lifetimes are near the lifetime calculated from Eq. (5), yet the observed width of the optical transitions remain far broader than the natural width. A common dye molecule such as rhodamine 6G has very broad optical absorption bands with widths on the order of 1000 A, but it has a measured radiative lifetime on the order of 10 nsec. Homogeneous lifetime broadening is clearly not the reason that the transitions are broad. The line width of the dye electronic transition must be the result of some combination of heterogeneous environment, coupling to vibrational transitions, and large-scale collective modes. An important goal of some low-temperature studies has been to separate these effects, because each is affected rather differently by temperature. 

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