Experiments measuring this quantity’s “time-dependent” form use a probe like coumarin to excite a solvent and track its reorganization, taking advantage of this quantity’s low value in ionic liquids. This quantity is plotted on the y-axis against a solvent’s orientational polarizability on a Lippert–Mataga plot. This quantity is low in wild-type proteins with a rigid chromophore environment that reduces relaxation. A negative version of this quantity appears in (*) photon upconversion. For a polarizable molecule, the causes of this quantity are represented by an up-arrow and a shorter down-arrow between electronic states on a Jablonski diagram. In contrast to Rayleigh scattering, changes in the vibrational energy level lead to this quantity and its “anti-” version. For 10 points, what quantity, which is the difference in maxima between the emission and absorption spectra of an energy transition, is vital to Raman spectroscopy? ■END■
ANSWER: Stokes shift [or downshift; accept anti-Stokes shift or upshift; prompt on Raman shift until “Raman” is read by asking “what is the more common form of that quantity?”; prompt on answers mentioning a frequency shift or wavelength shift; prompt on delta-nu or delta-lambda or delta-upsilon; prompt on delta or shift]
<KP, Chemistry>
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