Second harmonic generation measurements

Lantz J M and Corn R M 1994 Time-resolved optical second harmonic generation measurements of picosecond band flattening processes at single crystal TiO, electrodes J. Phys. Chem. 98 9387-90... 

Scheme 1. Apparatus for powder second harmonic generation measurements...

From Eq. (30) we can see that by varying the interaction length inside of the sample, the output intensity at frequency 2w will be changed. This is the basic idea behind most Second-Harmonic Generation measurement techniques. 

The non-centrosymmetric ordering of benzylquinuclidinium structure directing agents inside the centrosymmetric IFR framework has been shown by single crystal X-ray diffraction and second harmonic generation measurements. The reasons behind this effect and the requirements of the zeolite structural architecture needed to show this ordering are discussed. 

Under the assumption that the first hyperpolarizability p (compare Section 5.2) is along the chain axis of polythiophene, Kurata et al. also found by SHG (second harmonic generation) measurements, that the polymer stand upright on a glass substrate surface. The angle between surface normal and the chain axes is decreased by increasing the substrate temperature with 0= 14° at rs b = 473 K. 

The refractive indices of M(CeH5)4 crystals (M = Si to Pb) are in the 1.58 0.05 range. The crystals are transparent from 325 to 1200 nm and are Class B second harmonic generators. Measurements of linear electro-optic effects show the rg3 coefficients to be in the range (17 + 1) X 10 m/V with half-wave retardation voltages of 5 kV [24]. 

In addition to nitro derivatives, polyphosphazenes with sulfonyl-based chro-mophores (259) and (260) have been prepared according to a post-azo coupling approach with 4-ethylsulfonylbenzenediazonium fluoroborate. Absorptions of these polymers are blue-shifted compared to the absorptions of the nitro analogues. NLO activities of poled films of (259) and (260) have been determined by second harmonic generation measurements. " ... 

Also, Zhu and coworkers reported preparing of two high Tg (250° and 258°) polyimides embedded with triphenyl imidazole chromophores. Simultaneous polymerization and poling was carried in situ. The second harmonic generation measurements technology yielded moderate das values of 15 pnW and 16 pnvV. The signals of these poled polymer films were reported to be without any decay at < 150° The relaxation starts rapidly over 195°. The half-decay temperatures, of the samples orientation are as high as 240° and 224° respectively. 

Fig. 5 Diffusion-limited adsorption exhibited by ionic surfactants with added salt Dynamic interfacial tension between an aqueous solution of 4.86 X 10 M SDS with 0.1 M NaCl and dodecane (open circles and left ordinate), adapted from ref. [13] Dynamic surface tension of an aqueous solution of 2.0xl0 M SDS with 0.5 M NaCl (squares and left ordinate), adapted from ref. [30] Surface coverage deduced from second-harmonic-generation measurements on a saturated aqueous solution of SDNS with 2% NaCl (filled circles and right ordinate), adapted from ref. [31]. The asymptotic dependence shown by the solid fitting lines is a footprint of diffusion-limited adsorption...

Ortega, J. Gallastegui, J. A. Folcia, C. L. Etxebarria, J. Gimeno, N. Ros, M. B. Second harmonic generation measurements in aligned samples of liquid crystals composed of bent-core molecules. Liq. Cryst. 2004, 31, 579-584. 

E. Second Harmonic Generation Measurement of Experimental Setup... 

Results of electric-field induced second harmonic generation measurements on thin polydiacetylene films performed at 1 064 ym and 1.907 ym are reported At 1 064 m one observes large internal polarization fields depending on the polymer thin film morphology No such polarization effects are observed at 1 907 ym. 

Naujok, R. R., D. A. Higgins, D. G. Hanken, and R. M. Com, Optical second harmonic generation measurements of molecular adsorption and orientation at the liquid-liquid electrochemical interface, J Chem Soc Faraday T, Vol. 91, (1995) p. 1411. 

Any surface or interface breaks the inversion symmetry and is therefore a possible source of second-order effects. Owing to their surface sensitivity, second-harmonic generation measurements have developed into a very useful tool for probing the orientation of organic molecules in well-structured monolayers, such as those obtainable by the Langmuir-Blodgett technique (see Table 6). The surface susceptibility may in general be written as... 

D. A. Higgins, R. R. Naujok, and R. M. Corn, Chem. Phys. Lett., 213, 485 (1993). Second Harmonic Generation Measurements of Molecular Orientation and Coadsorption at the Interface between Two Immiscible Electrolyte Solutions. 

Such an approach has been used to determine the average a-relaxation time based on second harmonic generation measurements [60, 61] and fluorescence recovery after pattern photobleaching measurements [62, 63]. 

---