Raman Ponderings

Fran Adar - June, 2008

This is the opening of a blog that I will be writing/hosting to encourage a dialog with everyone and anyone involved in or interested in Raman spectroscopy, especially its applications for routine analysis. As you are probably aware, the field has undergone an awakening since the introduction in 1990 of the holographic notch filters that enables the production of benchtop-sized instruments. At that time it was realized that much of the complexity of the instrumentation could be reduced, enabling easier use, which promoted the development of real-world applications that previously had been very academic. A survey of journals such as Applied Spectroscopy and the Journal of Raman Spectroscopy, and of conferences such as the Pittsburg Conference, FACSS (Federation of Analytical Chemists and Spectroscopists Society) and EAS (Eastern Analytical Symposium) indicate the breadth of these applications Ė contaminant analysis, polymer characterization, cultural heritage (analysis of artifacts and their conservation), semiconductors, nanomaterials, corrosion, catalysis, ceramics, and the list goes on.

What people are asking is what is the future? Is the technology going to move further out of the lab? The prediction in 1990 was that 1000ís to 10ís of thousands of instruments would be acquired. It appears that that has not happened. Where are we now? There are fiber-coupled systems used for remote measurements, especially on manufacturing process lines. There are smaller, simpler systems, some hand-held for applications such as forensic analysis and incoming product testing. SERS (surface enhanced Raman scattering) is out there teasing us with its enhancements of 6 to 14 orders of magnitude. People are applying it to forensic analysis. How well is it working? Is it quantitative? Are you involved in any of these, or any other dedicated application where Raman is having an impact? If so, please give us your input. This is the whole point behind Ramanweb, this blog, and the companion forum. We want this to be a forum for a conversation in the community that can spur the continuing growth of Raman and the development of Raman applications. Meanwhile, I will post my thoughts in the next entry, and look forward to the thoughts of well known Raman practitioners in future guest blogs.

Why am I writing this? (My colleagues encourage me to tell you who I am, in case you do not know me.) My career has paralleled this instrumentation evolution that I mentioned in the first paragraph. I did my Ph.D. (1972) at U Penn (physics) on a home built 1.5m double mono that we aligned with plumberís wrenches. I moved to Biophysics and set up a resonance Raman facility to study interactions between hemes on functioning mitochondrial membranes. I came to Instruments SA (now HORIBA Jobin Yvon) to explore the applications of the Raman microscope in 1978. At that time the spectrum was excited by a water-cooled laser, the dispersion was on a 1m double mono, and the output was a strip chart recorder (hope that your pen did not run out of ink!). Fast forward to 1995 by which time most large monos were replaced with compact spectrographs and multichannel detectors, the excitation lasers were usually air-cooled, and the output was through a desk-top computer whose power provided enhanced spectral treatment functions rivaling the workstations of the 1980ís. Now in my lab I see lasers the size of cigarette packs and complete systems the size of a PC and smaller. I have been fortunate to have been working in the field during these innovations, and being able to apply the new capabilities to all types of materials.