摘要:

AbstractA multi‐purpose instrument which allows the recording of confocal micro‐Raman, micro‐SERS and micro‐fluorescence spectral images of sample areas from 5 × 5 to l50 × l50 μm with a lateral resolution ofca.0 3 μm and an axial resolution ofca.1 μm was developed. The instrument is a combination of two spectrometers both coupled to the same microscope, motorized sample stage, confocal entrance chamber, macro‐sample chamber and CCD detector. The first spectrometer includes a double monochromator coupled with a spectrograph and exhibits the properties of a typical high‐resolution Raman instrument permitting measurements of the low‐wavenumber regions of the spectra. The second spectrometer includes a Notch filter and a spectrograph equipped with two interchangeable low‐dispersion gratings and exhibits the properties of a high‐luminosity spectrometer, suitable for low resolution, over a wide spectral range and highly sensitive micro‐Raman and microfluorescence measurements. The choice of spectrometer most suitable for a particular application can be made automatically without additional prealignment of the system. The system of optical scanners operating in the confocal mode and two‐dimensional CCD detection allow the accumulation of spectra from hundreds of points of the sample under the microscope simultaneously. A computer‐controlled scanning sample stage and a system using a ‘scanning line’ of the laser beam allow fast recording of well resolved confocal spectral images (CSI) without sample degradation. Conventional images of species could be recorded with a TV–CCD camera through the microscope optics. The software supports all stages of CSI recording and allows the combined treatment of conventional and spectral images including their spatial calibration and conversion of spectral image into a conventional image, to assign point‐by‐point the spectral data to the conventional image. The applicability of the instrumentation and techniques to the study of polymeric materials, industrial samples and fluid inclusions in minerals was demonstrated. Spectral images based on the micro‐SERS analysis of an antitumour drug adsorbed on the hydrosol were recorded and are discussed in terms of their application to the mi

ISSN:0377-0486    

DOI:10.1002/jrs.1250250733

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractAmong the nucleosides, guanosine shows an anomalous behaviour which has been related to various factors (conformation, H‐bonding, self‐association, etc.), which characterize this nucleoside in relation to the others. It also easily forms a gel, the structure of which is well known. This work concerns the Raman vibrational spectroscopic characterization of the reactivity of guanosine N‐7, which is one of the main factors responsible for the anomalous behaviour of guanosine. For this purpose, some of its acid–base solid complexes and strongly acidic aqueous solutions were studied. In particular, this study considers the two Raman bands at about 1480 and 1540 cm−1, attributable to vibration modes with prevailing imidazolic character, N‐7 of free guanosine or bonded guanosine, respectively. In addition, the acid–base interaction via the H‐bond of N‐7 and the proton transfer in relation to the ΔpKa. of the interacting

ISSN:0377-0486    

DOI:10.1002/jrs.1250250734

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe temperature‐dependent vibrational infrared and Raman spectra of 20% solutions of decylammonium chloride in H2O (D2O) were studied. According to previous work, phases SIand SIIwere identified in the low‐temperature range. Molecular and supermolecular structures were derived. The upper shift (Δν = 12 cm−1) of the Raman‐active antisymmetric stretching CH2mode (d−) and its narrowness are peculiar and specific signals of a specific structure. It is proposed that the phase transition SI→ SIIis originated by the onset of a conformational flexibility generally described as twistons or conformational solitons. No evidence was found that the alkyl residues have librational freedom abo

ISSN:0377-0486    

DOI:10.1002/jrs.1250250735

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractChanges in the wavenumbers of the anisotropic and isotropic components of the CO stretching band in the Raman spectrum of LiClO4and Lil solutions in acetone were investigated. The non‐coincidence values defined as Δν = νaniso– visoof the CO band in LiCIO4solutions were positive for bulk acetone and negative for the acetone‐shared ion pairs. In LiI solutions, where the separation of bulk acetone was not possible, the non‐coincidence values changed from positive to negative with increasing concentration of LiI. A mechanism for the non‐coincidence cha

ISSN:0377-0486    

DOI:10.1002/jrs.1250250736

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe interaction between water and polyelectrolytes was investigated using aqueous dextran sulphate systems. The results indicated that the hydrogen‐bonding network of water in the system is affected by the presence of a highly charged polyanion with both surface hydrophobic and hydrophilic sites. This is reflected in the spectral profile of the OH stretching mode of water in the region 3000–4000 cm−1. Comparison with aqueous sodium methyl sulphate and sodium sulphate systems suggests that two regions of water are present in the dextran sulphate system. Water in the region associated with the hydrophobic carbohydrate skeleton appears to be more strongly hydrogen bonded than bulk water whereas that in the vicinity of the hydrophilic SO3−groups is more weakly hydrogen bonded. Variations in the vibrational spectra were dependent on the extent of the different populations of water present and can be explained by invoking the concepts of long‐range intermolecular coupling. Analysis of the dextran skeletal bands in the region 750–1850 cm−1confirmed that the SO3−sites play an important role in the hydration of dextran sulphate. The presence of two symmetric SO3−stretching modes in the Raman spectra of these systems, both of which are sensitive to the hydration state of the molecule, has been explained in terms of a model based on

ISSN:0377-0486    

DOI:10.1002/jrs.1250250737

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

ISSN:0377-0486    

DOI:10.1002/jrs.1250250702

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY