Three pulse echo peak shift

Passino S A, Nagasawa Y, Joo T and Fleming G R 1997 Three-pulse echo peak shift studies of polar solvation dynamics J. Phys. Chem. A 101 725-31... 

Figure 6. Theoretical [98] and experimental [10] three pulse echo peak shifts as a function of waiting time t2, for HOD/D2O at room temperature.

Thus in this case the peak shift t does not decay to zero. Figure 17 shows three-pulse echo peak shift data for a dye molecule, IR144, dissolved in ethanol and a plastic matrix (glass), PMMA, at room temperature. At long... 

Figure 19. Comparison of calculated and measured signals using the M(t) shown in Fig. 18. (a) Three-pulse echo peak shift, (b) transient grating, and (c) transient absorption. A pulse duration of 16 fs (20 fs for transient grating) and a detuning of 230 cm-1 are used in the calculated signals. The peak near T = 0 in the transient grating and transient absorption signals, usually referted to as the coherent artifact, arises from the ultrafast decay (sum of intramolecular vibrational contribution and -100 fs ultrafast solvation dynamics) in M(t).

The three-pulse-echo peak shift is another two-dimensional echo technique, so far applied only to electronic transitions (122,123). It integrates over r3 and keeps rx and r2 as the time variables. The data are reduced by tracing the maximum in as a function of r2, resulting in a onedimensional decay curve. Although the implementation of this type of echo spectroscopy is quite different, the essential information content is much the same as in the Raman echo approach. 

Figure 26. Comparison for the absorption spectrum and three-pulse-echo peak shift determined from experiment for the B850 band of LH2 with that calculated using the model described in the text. Parameters are the same as in Fig. 23 right panel), plus a spectral density (see Ref. 40).

Shortly thereafter came reports of integrated three-pulse photon echoes, especially using the echo peak shift to provide information about spectral diffusion [21, 23]. In one experiment [10, 23] the peak shift shows an intriguing oscillation at short times with a period of about 180 fs, followed by a slower relaxation with a decay time of 1.4 ps. The three-pulse echo amplitude can also be heterodyned, leading to 2DIR experiments [24 26]. The latter experiments provide a wealth of information, and there are several ways to extract the desired spectral diffusion dynamics [149]. 

The first type of experiment we describe is a stimulated three-pulse echo (3PE) peak shift measurement. In this experiment, the two echo signals symmetrically placed at -kj + k2 + kj and k - k2 + k3 are recorded simultaneously. A sequence of such signals recorded at different values of the population period T is shown in Fig. 14 (see Fig. 12 during the period T,... 

Figure 18. The normalized electronic transition frequency correlation function M(t) 1= S(i)] obtained from the experimental three-pulse photon echo peak shifts and transient grating data for IR144 in ethanol (—) total W(t) ( ) ultrafast Gaussian component in M(t) ( ) oscillatory component that arises from intramolecular vibrational motion.

Figure B2.1.10 Stimulated photon-echo peak-shift (3PEPS) signals. Top pulse sequence and interpulse delays t and T. Bottom echo signals scanned as a function of delay t at three different population periods T, obtained with samples of a tetrapyrrole-containing light-harvesting protein subunit, the a subunit of C-phycocyanin.

Fig. 11.12 Dependence of three-pulse photon-echo peak shift on delay time t2, calculated as in Eig. 11.11 using the Kubo relaxation function (Eq. 10.69) with -r = 10, 20 or 40 time units as indicated and a = 0.05 (A) or 0.1 (B) reciprocal time units...

Nagasawa, Y., Watanabe, Y., Takikawa, H., Okada, T. Solute dependence of three pulse photon echo peak shift measurements in methanol solution. J. Phys. Chem. A 107, 632-641 (2003)... 

The multiple-quantum (MQ)/MAS NMR is one of the 2D NMR methods, which is capable of averaging out the second-order quadrupolar interaction in nuclei with spin > 1/2 such as H, "B, O, etc. The "B MQ/ MAS NMR measurements on boron as contained in silyl-carborane hybrid Si-based polymer networks considered here. The molded samples are cut into small pieces to insert them into a 4-mm NMR rotor and spun at 12 kHz in a MAS probe. The observation frequency of the "B nucleus (spin number I = 3/2 and isotope natural abundance = 80.42%) is 96.3 MHz. Excitation of both the echo (—3Q) and anti echo (+3Q) coherences is achieved by using a three-pulse sequence with a zero quantum filter (z-filter). The widths of the first, second, and third pulses are 3.0 4.1 ps, 1.1-1.6 ps, and 19-28 ps, respectively. The z-filter is 20 ps. The recycle delay time is 6-15 s and the data point of FI (vertical) axis is 64 and for each the number of scans is 144. Then, the total measurement time is 15-38 h. The phase cycling used in this experiment consists of 12 phases. Boron phosphate (BPO4 3 = 0 ppm) is used as an external standard for "B. The chemical shift value of BPO4 is —3.60 ppm from BF3 O(C2H5)2 which is used as a standard reference in " B NMR in the liquid state. The transmitter frequency of " B is set on peak of BPO4 for a trustworthy chemical shift after Fourier transform." " ... 

More reeently, higher-order nonlinear optical measurements such as three-pulse photon eeho peak shift measurements have been carried out to study the SD. Fleming and co-workers studied such three-pulse photon echo from the dye molecule eosin in water. They found that a substantial amplitude (about 60%) of aqueous solvation oecurs within 30 fs. A three-exponential fit (up to 100 ps) to the data of eosin in water yields time eonstants of 17 fs (73%), 330 fs (15%), and 3 ps (12%). Analysis... 

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