Raman spectra of undeuterated and deuterated rachis from a fowl feather was observed with 488 nm excitation in the 400-1800 cm(-1) region. Fowl feather rachis and barbs were subjected to a polarized Raman microscopic examination with excitation at 785 nm. From the observed frequencies, intensities, and scattering anisotropies of the 20 Raman bands, and on the basis of known Raman tensors of the 10 localized molecular vibrations, conformations, and orientations of the polypeptide main chains, tyrosine, phenylalanine, tryptophan residues, and disulfide linkages of the protein molecules in the feather were elucidated.

Surface-enhanced Raman scattering (SERS) of dipping films of azobenzene-containing long-chain fatty acids, nAmH (n=8, 12, m=3, 5), on silver mirrors measured with a wide range of excitation wavelengths in the 457.9–1064nm region is reported. The obtained Raman spectra show great SERS effect even with the 1064nm excitation, and the excitation with 457.9, 476.5, and 488.0nm gives surface-enhanced resonance Raman scattering (SERRS) due to the resonance effect of the symmetry-forbidden n–π∗ transition of the azo group. Of particular note in the present study is that the SERS spectra with the excitation in the 532–1064nm region yield Raman bands whose frequencies are almost identical to those bands in Raman spectra of nAmH in solid state while the SERRS spectra with the excitation in the 457.9–514.5nm region show not only a set of bands which correspond to those of nAmH in the solid state but also a set of bands whose frequencies show a significant shift from those of the bands of nAmH in the solid state. These observations lead us to conclude that there are two kinds of molecular aggregates in the dipping films of azobenzene-containing long-chain fatty acid in which azobenzene moieties are condensed to form small bundles.

The Pseudomonas bacteriophage Pf1 is a long ( approximately 2000 nm) and thin ( approximately 6.5 nm) filament consisting of a covalently closed, single-stranded DNA genome of 7349 nucleotides coated by 7350 copies of a 46-residue alpha-helical subunit. The coat subunits are arranged as a superhelix of C(1)()S(5.4)() symmetry (class II). Polarized Raman and polarized FTIR spectroscopy of oriented Pf1 fibers show that the packaged single-stranded DNA genome is ordered specifically with respect to the capsid superhelix. Bases are nonrandomly arranged along the capsid interior, deoxynucleosides are uniformly in the C2'-endo/anti conformation, and the average DNA phosphodioxy group (PO(2)(-)) is oriented so that the line connecting the oxygen atoms (O.O) forms an angle of 71 degrees +/- 5 degrees with the virion axis. Raman and infrared amide band polarizations show that the subunit alpha-helix axis is inclined at an average angle of 16 degrees +/- 4 degrees with respect to the virion axis. The alpha-helical symmetry of the capsid subunit is remarkably rigorous, resulting in splitting of Raman-active helix vibrational modes at 351, 445 and 1026 cm(-)(1) into apparent A-type and E(2)()-type symmetry pairs. The subunit tyrosines (Tyr 25 and Tyr 40) are oriented with phenoxyl rings packed relatively close to parallel to the virion axis. The Tyr 25 and Tyr 40 orientations of Pf1 are surprisingly close to those observed for Tyr 21 and Tyr 24 of the Ff virion (C(5)()S(2)() symmetry, class I), suggesting a preferred tyrosyl side chain conformation in packed alpha-helical subunits, irrespective of capsid symmetry. The polarized Raman spectra also provide information on the orientations of subunit alanine, valine, leucine and isoleucine side chains of the Pf1 virion.

Raman mapping images have been obtained for compatibilized and uncompatibilized polymer blends in films of Nylon 12 and high density polyethylene (HDPE) (blend ratios were 20/80, 50/50, and 80/20). A total of 400 Raman spectra were measured for each sample with areas of 100 μm 2 and in step sizes of 0.5 μm (for 20 × 20 probe spots). To develop the Raman mapping images, the intensity ratio of two bands, a band at 1635 cm −1 due to Nylon 12 (amide I mode) and that at 1296 cm −1 arising from both HDPE and Nylon 12 (CH 2 twisting) is used. The Raman mapping images of the uncompatibilized polymer blends show a clear “sea-island” structure while those of the compatibilized polymer blends exhibit a compatibilized structure. The Raman mapping images enable simultaneous exploration of the morphology and molecular structure of the blends. We have also developed a Raman mapping image that represents the variation of crystallinity in the uncompatibilized film.

This article reports the outline of a new portable Raman imaging probe and its applications. This probe may be the smallest and lightest Raman imaging probe in the world. It is equipped with an interchangeable long-working distance microscope objective lens. The irradiation area is about 45 and 90μm and the spatial resolution is 1μm. In the present study, the Raman imaging probe was used to obtain a Raman image of diamond particles and a Raman mapping of carotenoid in Euglena.

We have investigated the surface geometry of azobenzene-containing long-chain fatty acids ( nA mH; n = 8, 12, m = 3, 5) adsorbed on silver and gold colloids as well as the interaction between nA mH and the two kinds of metal colloidal surface by means of near-infrared and visible surface-enhanced Raman scattering (SERS). The 488.0 and 514.5 nm excited Raman spectra of nA mH adsorbed on silver colloid and the 1064 nm excited Fourier transform (FT)-Raman spectrum adsorbed on gold colloid show a marked SERS effect. The lowest concentration at which the SERS signals were observed was 10 −10 and 10 −8 M for the silver and gold colloids, respectively, in the present study. The 488.0 nm excited SERS spectrum of 12A3H adsorbed on silver colloid is very similar to a Raman spectrum of 12A3H in chloroform, while the 1064 nm excited SERS spectrum of 12A3H adsorbed on gold colloid is quite different; a number of new bands appear, and the relative intensity of bands changes markedly in the 1064 nm excited SERS spectrum. Probably, a chemical mechanism contributes significantly to the emergence of the SERS effect for 12A3H on gold colloid. Particularly striking in the SERS spectrum of 12A3H adsorbed on gold colloid is the observation that bands at 1586, 1166, and 834 cm −1 due to the phenyl ring modes show remarkable enhancement. It seems likely that the COO − group is adsorbed directly on the silver colloid surface, while one of the phenyl groups is adsorbed directly on the gold colloid surface. The effect of the particle size on the SERS intensity has been explored for 12A3H on gold colloid. It was found from the frequency of the -N=N- stretching band that 12A3H assumes a cis conformation on the gold colloid with the smaller particle size.

Raman spectra of single cells of Euglena and Chlamydomonas have been examined with 514.5 nm excitation at various points within the cells. At every point, two strong bands, which are assignable to carotenoid, appeared at 1530 and 1159 cm(-1). By the use of a Raman mapping system, the Raman intensity at 1530 cm(-1) has been plotted against the (x,y) coordinate representing a location within the cell, It has been shown that, for both algae examined, the eyespot has a prominently high carotenoid content, and a small amount of carotenoid is uniformly distributed among the chloroplast. The spatial resolution of the mapping system has been shown to be higher than 1 mu m, and the Chlamydomonas eyespot has an elongated shape of 1 mu m x 2 mu m. By use of a polarizer, the carotenoid chains in the Chlamydomonas eyespot have been found to be aligned along its long axis, which is parallel to the body axis.

The 488.0 and 1064 nm-excited Raman spectra have been measured for dipping films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane (octadecyl-TCNQ) and docosylpyridinum-TCNQ salt and mixed-stack charge transfer films of octadecyl-TCNQ doped with 3,3',5,5'-tetramethylbenzidine (TMB) deposited on silver mirror. The 488 nm-excited Raman and 1064-nm excited FT-Raman spectra of dipping films of octadecyl-TCNQ and docosylpyridinum-TCNQ salt and CT film of octadecyl-TCNQ doped with TMB on the silver mirror gave very intense Raman bands with a high signal-to-noise ratio owing to the SERS effect. From the frequency of a C equivalent toN stretching band of the CT film of octadecyl-TCNQ doped with TMB on silver mirror, the degree of CT can be calculated to be 0.42, suggesting that the CT film is in a quasi-neutral state. The C equivalent toN stretching band of the dipping film of docosylpyridinium-TCNQ salt indicates the strong interaction of TCNQ group with silver minor surface.

Raman, surface-enhanced Raman scattering (SERS) and ultraviolet-visible-near infrared (UV-vis-NIR) spectra have been measured for Langmuir-Blodgett (LB) films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane (octadecyl-TCNQ) and mixed-stack charge transfer (CT) films of octadecyl-TCNQ doped with 3,3',5,5'-tetramethylbenzidine (TMB) deposited on CaF(2) plates and Au-evaporated glass slides. The 488.0 nm-excited Raman spectra of one-layer LB and CT films of octadecyl-TCNQ deposited on the Au-evaporated glass slides show a high signal-to-noise ratio owing to surface-enhanced Raman scattering (SERS). These Raman spectra are resonanced with absorption bands arising from intramolecular excitations of TCNQ molecules. Thus, we suggest that the 488.0 nm-excited Raman spectra of the LB and C-T films deposited on the Au-evaporated glass slides are surface-enhanced resonance Raman (SERRS) spectra. The UV-vis-NIR spectrum of the CT film on the Au-evaporated glass slide is largely different from that of the film on the CaF(2) plate. However, their Raman spectra are very close to each other, although the SERRS spectrum of the CT film on the Au-evaporated glass slide is more enhanced than the resonance Raman spectrum of the film on the CaF(2) plate. It seems that the structure of octadecyl-TCNQ and TMB changes little with the substrates, but that the mechanism of CT is perturbed by the interaction between the first layer and the substrate. (C) 1999 Elsevier Science B.V. All rights reserved.

Raman, FT-Raman and ultraviolet-visible-near infrared (UV-vis-NIR) spectra have been measured for mixed-stack charge transfer (CT) films of 2-octadecyl-7,7,8,8-tetracyanaquinodimethane (octadecyl-TCNQ) doped with 3,3',5,5'-tetramethylbenzidine (TMB) deposited on CaF2 plates and Au-evaporated glass slides. The 1064 nm-excited FT-Raman spectra can be observed clearly even for the one-layer CT films deposited on CaF2 plates because the excitation wavelength is located within a broad CT band centered near 1550 nm. The degree of the charge transfer determined by a shift of the CEN stretching band of the TCNQ chromophore suggests that the CT complex films are in a quasi-neutral state.

By observing the temperature dependence of the HOH bending band of trehalose dihydrate, it is found that the property of the bound water molecules changes from the ice-like water to liquid-like one at 70 °C. This finding indicates that the trehalose/water complex behave like a small size of water cluster.

Two-dimensional near-field Raman spectra and topographic images of the polydiacetylene surface are measured simultaneously by using a near-field Raman spectrometer. The spectra (located 100 nm apart) have different spectral features. The peak intensity ratio of two C=C peaks at 1520 and 1457 cm−1 does not correlate with the topographic image and shows differences in the subwavelength scale. These differences can be interpreted as spatial differences in the number of successive bonds on the polydiacetylene surface. In contrast, the near-field Raman intensity of the C=C bond at 1457 cm−1 correlates strongly with the topographic image. This phenomenon can be interpreted as a change in the efficiency of collecting Raman scattering light.

A general method is presented for determining the shape and orientation of the Raman tensor of a molecule in a uniaxial crystal using a Raman microscope. First, equations are derived to connect the Raman tensor components (alpha-xx, alpha-yy, etc.) of a molecule to the Raman tensor components (alpha-aa, alpha-cc, etc.) of a crystal that is composed of molecules in a uniaxial arrangement, with an orientation specified by the two angles chi and theta. Next, a method is presented to obtain a correct set of values of the intensity ratios I(ac)/I(aa) and I(cc)/I(aa) from observed values of the intensity ratios measured with a Raman microscope. To augment the experimental data, the depolarization ratio rho (for a completely random molecular orientation) is plotted as a function of r1 = alpha-xx/alpha-zz and r2 = alpha-yy/alpha-zz, so that a possible set of r1 and r2 values can be found from an observed value of rho. The method has been applied to an aspartame IIA crystal (P4(1)). A set of values of r1, r2, chi and theta has been determined for each of the following Raman fundamentals: 1741 cm-1 (ester C = O stretch), 1667 cm-1 (amide I), 1275 cm-1 (amide III) and 1204 cm-1 (C-C(phenyl) stretch), excited at 488.0 nm.

A fowl feather barb 10 μm in thickness was subjected to a polarized infrared spectroscopic measurement by the use of a microscopic device. Nearly 50% of its peptide groups were found to give the 1633 and 1684 cm−1 bands characteristic of the antiparallel-chain pleated sheet structure, and the remaining 50% gave the 1659 cm−1 band assignable to unordered polypeptide chains. The orientation of the pleated sheet was determined to be on average θ = 52° and χ = 39°, where θ and χ are the angles for the transformation of the XYZ coordinate system fixed on the pleated sheet and the abc coordinate system fixed on the sample barb. The Raman spectra of the barb were also examined with another microscopic device and a 488.0-nm laser beam. A sharp aa component of the Raman scattering tensor was observed at 1667 cm−1. Based on this fact, a revised set of parameters for the vibrational couplings among the peptide groups in the pleated sheet has been proposed. Some discussions have been made on the amide I Raman tensor of the antiparallel-chain pleated sheet. Key words: fowl feather barb, Raman microscope, infrared microscope, antiparallel-chain pleated sheet, Raman scattering tensor.

Raman spectra of Y1-xCa(x)Ba2Cu4O8 (x = 0.0, 0.02, 0.05 and 0.1) ceramic samples synthesized under high oxygen pressure were investigated. Seven clear peaks assigned to A(g) modes were observed for the sample with x = 0. With increasing x, the peaks at 238 cm-1, 332 cm-1, 430 cm-1 and 590 cm-1 were broadened. The origin of the broadening of the peaks at 238 cm-1 and 590 cm-1 is considered to be the destruction of the double Cu-O chains due to the substitution of Ca for Y.