Vavilov

Vernadsky Institute of Geochemistry and Analytical Chemistry RAS 19, Kosygin Str, 119991 Moscow, e-mail abors mail.ru - Prokhorov General Physics Institute RAS 38, Vavilov Str, Moscow... 

Russian Academy of Sciences 199991, GSP-1, Moscow, Vavilov St., 28 e-mail analyst ineos.ac.ru... 

Between 1923 and 1927, the concepts of quantum efficiency (number of photons emitted divided by number of photons absorbed by a sample) and quantum yield (fraction of excited molecules that emit) had been defined and values determined for many compounds by Vavilov (34). The quantum yield indicates the extent that other energy loss mechanisms compete with emission in an excited molecule. Although the quantum yield is influenced by the molecular environment of the emitter, for a given environment it depends on the nature of the emitting compound and is independent of concentration and excitation wavelength, at least at low concentrations (35). Tlius, it serves as another measurable parameter that can be used to identify the compounds in a sample and also, because of its sensitivity to the surroundings of the luminophore, to probe the environment of the emitter. 

Any questions and comments may be sent to the authors at The Center for Russian Environmental Policy (Moscow, 119991, Vavilov Street, 26 fax (095) 952-80-19 e-mail Yablokov online.ru fedorov online.ru). 

Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov St. 28,... 

At an MEK concentration greater than 1 M, both the dynamic and the static quenching mechanisms have to be taken into account. Therefore, Frank and Vavilov s model of combined static and dynamic quenching model (28),... 

The probability of intramolecular energy transfer between two electronic states is inversely proportional to the energy gap, AE, between the two states. The value of the rate constant for radiationless transitions decreases with the size of the energy gap between the initial and final electronic states involved. This law readily provides us with a simple explanation of Kasha s rule and Vavilov s rule. 

S. J. Vavilov Excitation-wavelength independence of the fluorescence quantum yield... 

S. J. Vavilov and W. L. Levshin First study of the fluorescence polarization of dye solutions... 

Russian Academy of Science Vavilov Str. 32 Moscow 117984 / Russia prasolov eimb.ru... 

Shatsky, V.S., Sobolev, N.V., Vavilov, M.A. 1995. Diamond-bearing metamorphic rocks of the Kokchetav Massif (northern Kazakhstan). Ultrahigh-Pressure... 

A. Nikitina str, 22, 170026, Tver, Russia Chemistry Department Indiana University, Bloomington, IN 47405, USA Nesmeyanov Institute of Organoelement Compounds ofRAS, Vavilov str., 28,... 

Institute of Organo-Element Compounds RAS Vavilov Strasse 28 119991 Moscow Russia... 

The independence of luminescence quantum yields on excitation wavelength is known as Vavilov s rule. There are however many exceptions to this rule, in particular for molecules which contain heavy atoms such as Br and I, or metals (e.g. organometallic complexes). The heavy atom effect makes intersystem crossings more efficient and these can compete with internal conversions. 

The heavy atom effect affects also the non-radiative transitions, as shown above in Figure 4.76. Transitions between higher excited states of different nominal multiplicities are efficient, so that the luminescence quantum yields depend on the excitation wavelength. (Vavilov s rule breaks down in such cases.)... 

C. Vavilov-Cherenkov Radiation and Photoradiation Reactions in Tracks... 

A charged particle emits Vavilov-Cerenkov radiation (VCR) when its velocity becomes greater than the speed of light in the medium, that is, when v > dn where nr is the refractive index of the medium. This is so when the energy of the particle is sufficiently high—for electrons in water it must be >270 keV. And though the contribution of VCR to the energy losses is small, it can nevertheless be essential in photosensitive media (see Section VIII.C). 

The second term in formula (5.23) is nonzero only if p2e(a>) > 1, which is the condition of existence of transversal waves in the medium. These waves are the Vavilov-Cherenkov radiation,211 so that second term gives us the losses of particle s energy on Vavilov-Cherenkov radiation. This radiation is observed in the frequency range where (w) is real [i.e., e2(w) = 0],148 and the absorption is negligible. In this case the second term is independent of b, and the particle s field has the form of waves propagating into infinity. If the absorption is large, the Vavilov-Cherenkov radiation is absorbed in the nearest vicinity of the point where it was produced. 

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