Optical induction decay

This free optical induction decay can be measured with a beat technique at time t = 0 the frequency w of a CW laser is switched from w =... 

Rhee H, JuneYG KZH et al (2009) Phase sensitive detection of vibrational optical activity free-induction-decay vibrational CD and ORD. J Opt Soc Am B 26 1008-1017... 

Figure 1. The effect of coherent excitation on hght transmission, (a) The incident and transmitted pulses through a sample having an optical density of 1.0. (b) The free induction decay created by the coherent excitations by the pulse in (a), (c) The Wigner distribution (see text) of the FID shown in (h).

E. Optical Free Induction Decay and Optical Nutation in a Multilevel System.. 481... 

The important point to note here is that the photon echo does not suffer from the triplet state bottleneck in the same sense as hole-burning or optical free induction decay. It is only the repetition rate in the photon-echo experiment that is limited by the triplet state decay rate. Morsink et al. showed that at low temperature ( 2 K) the photon-echo hfetime of dilute PTC-A,4 and PTC-d,4 in p-terphenyl crystals is identical to the fluorescence lifetime. This implies that at this temperature pure dephasing processes are absent. The homogeneous linewidths are therefore 5.9 MHz (PTC-rf,4) and... 

In molecules, as noted by de Vries and Wiersma, the application of free induction decay to study optical dephasing may be frustrated by the presence of an intermediate triplet state. The level scheme, which is representative for most molecules with an even number of electrons, is shown in Fig. 26. For an applied laser field E =EQCOs t-k ), that is resonant with the (2 <- 1) transition, we may write, in the RWA approximation, the following steady-state density matrix equations, which describe the coherent decay after laser frequency switching ... 

In Fig. 27 we reproduce a low-temperature optical free induction decay signal of pentacene-A,4 in p-terphenyl. The insert in the figure shows that... 

Fig. 27. Optical free induction decay signal of pentacene-/ii4 in p-terphenyl at 1.5...

Fig. 28. The optical free induction decay observed in pentacene (0, origin) at 1.8 K and 400 pW of laser power. The computer fit provided a value of 45 2 ns for 7 from the observed transient decay. (After Ref. 71.)...

Fig. 7.24 (a) Optical nutation in CH3p observed with CO2 laser excitation at A = 9.7 pm. The Rabi oscillations appear because the Stark pulse lower trace) is longer than in Fig. 7.23. (b) Optical free-induction decay in I2 vapor following resonant excitation with a cw dye laser at = 589.6 nm. At the time = 0 the laser is frequency-shifted with the arrangement depicted in Fig. 7.22 by Au = 54 MHz out of resonance with the I2 transition. The slowly varying envelope is caused by a superposition with the optical nutation of molecules in the velocity group Vz = o) — (oo)/k, which are now in resonance with the laser frequency oj. Note the difference in time scales of (a) and (b) [705]... 

In the case of coherent laser light, the pulses are characterized by well-defined phase relationships and slowly varying amplitudes (Haken, 1970). Such quasi-classical light pulses have spectral and temporal distributions that are also strictly related by a Fourier transformation, and are hence usually refered to as Fourier-transform-limited. They are required in the typical experiments of coherent optical spectroscopy, such as optical nutation, free induction decay, or photon echoes (Brewer, 1977). Here, the theoretical treatments generally adopt a semiclassical procedure, using a density matrix or Bloch formalism to describe the molecular system subject to a pulsed or continuous classical optical field, which generates a macroscopic sample polarization. In principle, a fully quantal description is possible if one represents the state of the field by the coherent or quasi-classical state vectors (Glauber, 1965 Freed and Villaeys, 1978). For our purpose, however. 

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