Applied Spectroscopy Reviews

Treado, Patrick J.; Morris, Michael D.

doi: 10.1080/05704929408000896pmid: N/A

Introduction Microscopies based on the vibrational spectrum of a molecule provide perhaps the closest approach to universally applicable, chemically selective contrast generation techniques. Infrared and Raman microscopic imaging both use the technology of light microscopy, although in modified form. The mid-infrared and the near-infrared are both employed for microscopic observation. Raman imaging uses the visible region. Like the underlying spectroscopies, infrared microscopy is more widely practiced than Raman microscopy. And like the underlying spectroscopies, each has its characteristic advantages and drawbacks.

Kopelman, Raoul; Tan, Weihong

doi: 10.1080/05704929408000897pmid: N/A

Introduction Optical microscopy and spectroscopy have long been key techniques in medicine, biology, chemistry, and materials science. Among their advantages are: 1. 1. Universality. All materials and samples attenuate light and have spectroscopic states. 2. 2. Noninvasiveness. Most often the sample is not altered in a microscopic and/or spectroscopic investigation. Moreover, biological samples usually can be studied in their native environment. Most chemical reactions are not perturbed by light of long enough wavelength. 3. 3. Real-time observation. Biological phenomena, chemical reactions, crystallization, and so on can be observed under the microscope as they happen in situ (even with one's eyes); spectroscopic measurements can be performed on line in an industrial process or other setting. 4. 4. Energy and chemical state resolution. The obvious advantages of spectroscopy and photochemistry, at ambient temperature, can be trivially added to the optical methods mentioned above. By contrast, this is not easily accomplished with other techniques such as electron microscopy or x-ray crystallography. 5. 5. Safety. Optical and spectroscopic analyses usually are very safe, and precautions are mostly limited to wearing optically protective eyeglasses. 6. 6. Low price. Optical microscopy is much cheaper than, say, electron microscopy; optical spectroscopy is usually a bargain compared with, say, NMR instruments. Obviously, there are exceptions. 7. 7. Speed, zoom, and human factors. Optical techniques are usually fast and can be extended even into the femtosecond time domain. They can be used from astronomical to microscopic distances. Preliminary or concomitant observations can be made using our most developed sense—sight, and in living color—even without the brokerage services of an analog or digital interface.

Odom, Robert W.

doi: 10.1080/05704929408000898pmid: N/A

Introduction Secondary ion mass spectrometry (SIMS) is a chemical analysis technique that employs mass spectrometry to analyze solid and low volatility liquid samples [1]. Although there are numerous configurations of SIMS instrumentation, the fundamental basis of SIMS analyses is the measurement of the mass and intensity of secondary ions produced in a vacuum by sputtering the surface of the sample with energetic ion or neutral beams. The sputtering beam is referred to as the primary beam and typically has a kinetic energy of several thousand electronvolts (keV). The primary beam removes atomic or molecular layers at a rate determined principally by the intensity, mass, and energy of the primary species and the chemical and physical characteristics of the sample [2]. Particle sputtering at the kiloelectronvolt level produces a variety of products including electrons, photons, atoms, atomic clusters, intact molecules, and distinctive molecular fragments. A small fraction of these sputter products are ionized, and these ions are the secondary ions in secondary ion mass spectrometry.