A facility to perform infrared microspectroscopy is under development at the NSLS of Brookhaven National Laboratory. The high brightness infrared light produced as synchrotron radiation makes a nearly ideal source for microspectroscopy. High quality spectra from 10 ,um sized areas can be acquired in less than 1 min. A description of the installation, microspectroscopy performance, and an example application are presented. 0 1995 American Institute of Physics.

The potentiality of synchrotron infrared microspectrometry was investigated for in situ analysis of fluid inclusions and volatiles of particular geological interest. Thanks to the intrinsic high brightness of the synchrotron infrared source, areas as small as a few μm2 can be probed, providing a high-contrast analysis of small inclusions in geological materials. We have identified organic components in such small volumes in their liquid and gaseous phase, thus allowing a deeper analysis of oil-water inclusions entrapped in diagenetic cements. Such detailed analysis opens up new perspectives in petroleum reservoir evolution studies. The high signal-to-noise ratio of spectra obtained in small volume allows a fast and accurate chemical mapping of the inclusion components. Drastic refraction effects preclude, at the present state, a quantitative analysis of either the volume or the thickness of the individual inclusions. Traces of volatiles such as CO2 and H2O are easily detected in the vitreous and gaseous part of the glass melt fluid inclusions. We have also profiled the hydroxyl concentration near a wall, and calculated the hydrogen diffusion coefficient in anhydrous minerals such as diopside.

The mid-infrared region (25-2.5 microns) is a very useful frequency range as most of the existing molecular groups have vibrational energies in this region. These intramolecular vibrational modes play an important role in analytical work, and are responsible for the widely recognized success of the infrared spectroscopic technique.Moreover, infrared microspectroscopy [1,2] is a microanalytical and imaging technique which achieves contrast via the intramolecular vibrational modes which are often referred to as the "fingerprint" modes. In such an approach, it is always highly desirable to achieve as high a spatial resolution as possible, although diffraction provides the ultimate limit. Using a conventional infrared thermal source, the resolution cannot be made as low as the diffraction limit would allow. This is due to the lack of energy at the sample position when closing the aperture down (typically below 15 to 10 microns).The use of synchrotron radiation has overcome those limitations [2,3]. Infrared synchrotron radiation is about 1 000 times brighter than globar sources, and therefore offers considerably improved signal to noise capabilities. Synchrotron radiation is also a polarized and pulsed (on the 100 picosecond timescale) source, that opens up new perspectives in analytical chemistry.In this article, we briefly describe the advantages of the synchrotron source. We will then present recent applications that illustrate the superiority of this technique, in various domains. As illustrated in figure 1, improving the lateral resolution is beneficial in three categories of experiments: (a) one can identify individual particles (Fig. 1a) to understand the degree of heterogeneity in distribution of compounds, as this will be exemplified in this article; (b) one can investigate the diffusion between two interfaces which is a major problem in many applications involving fabrication processes (Fig. 1b); and (c) one can record infrared spectra from a small area, and scan over a large domain (Fig. 1c), to obtain images of small samples using chemical contrast techniques. We will show how this last experimental scheme has been successfully used in Biology and Petrography.

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