Nonlinear Optics of Organic and Polymer Materials

Abstract

Over the past decade the study of nonlinear optical processes in organic and polymer systems has enjoyed rapid and sustained growth. One indication of that growth is the increase in the number of articles published inrefereed society journals. The four-year period 1980–83 saw the publication of 124 such articles. For the four-year period a decade later the production of articles in the field had grown to 736—nearly a sixfold increase. In part, the rapid growth of the field can be attributed to the technological promise and interesting physical properties of these materials. Because of their large optical nonlinearities and mechanical, chemical, thermal and optical stability, organic nonlinear optical materials are the leading practical materials for fabricating optoelectronic devices. They also have proven to be excellent subjects in which to study many-body electron correlation effects and exotic states like polarons, excitons and even coherently propagating multiexciton strings.

Thermal Chemistry of Styrene on Si(100)2×1 and Modified Surfaces: Electron-Mediated Condensation Oligomerization and Posthydrogenation Reactions

“…40 In this case, the condensation oligomerization process was marked by a shift in the TDS maximum for hydrogen evolution to a higher temperature (910 K) relative to that of recombinative desorption from monohydrides abstracted from adsorbed pyridine monomers or its smaller fragments (∼800 K). Together with the small shoulder appearing at 930 K of the mass 2 TDS profile (Figure 5d), the similarity in the observed shift in the desorption maximum for mass 4 in styrene-ring-d 5 (Figure 5c) suggests electron-induced oligomerization of styrene at RT, as in the case proposed for pyridine. 40 In accord with our previous TDS experiments, 51 the present work appears to support the general observation that the larger the size of the unsaturated organic adsorbate, the higher the temperature for hydrogen evolution.…”

“…The desorption maxima for both molecular and dehydrogenated products were also found to be shifted by 100 K to 670 K, similar to the desorption maximum of dihydride (650 K). We have also performed the same TDS experiment for 100 Langmuir exposure of styrene-ring-d 5 In Figure 6, the two intense TDS features of mass 2 with maxima at 680 and 800 K for the posthydrogenated styrened 8 /Si(100)2×1 sample are found to be similar to those arising from recombinative thermal desorption, respectively, from dihydride and monohydride on a H-terminated Si(100) surface. 46,47 Two mass 4 TDS features with maxima located at 820 and 900 K are found for the posthydrogenated sample ( Figure 6).…”

“…For completeness, we also compare in Figure 5 the TDS profiles for molecular desorption (mass 109) and desorption of dissociative products (masses 28, 4, and 2) for the 2×1 surface with those for the modified surfaces of Si(100) exposed to 10 Langmuir of styrene-ring-d 5 at RT. The amorphous Si (a-Si) surface was produced by ion sputtering in 4 × 10 -5 Torr of Ar at 1 keV ion impact energy for 20 min, while the oxidized Si(100) surface was obtained by exposing a clean 2×1 surface with 100 L of O 2 at RT.…”

“…43 After removal of this contribution due to C 2 D 2 (with its origin likely coming from the dissociation of the phenyl group of the adsorbed styrene-ring-d 5 ) in the mass 26 TDS profile, we obtain a similar amount of contribution from the parent mass of C 2 H 2 (as that originated from C 2 D 2 ), which could come from dissociation of the vinyl group. Given the lack of any discernible features of mass 26 at the corresponding temperatures, the other TDS features of mass 28 at 440 and 900 K (Figure 5b) could be attributed to dissociative desorption of C 2 D 2 from the phenyl group of adsorbed styrene-ring-d 5 . The increase in the mass 28 TDS profile for a-Si surface with respect to that for the 2×1 surface (Figure 5b) suggests that there are evidently more active sites available for dissociation on the a-Si surface.…”

“…2 Due to their unique physical and electronic properties, organic semiconductors represent a viable material for improving both the functionality and miniaturization, 3 and they promise new technological applications in the emerging nanoelectronics industry. [4][5][6][7] Many applications of organic semiconductors rely on the synthesis of fully conjugated organic polymers, or conducting polymers. 8 Molecular engineering of π-conjugated oligomers and polymers has therefore become especially important to producing well-characterized organic nanoscale structures and devices.…”