Tutorials
Spectroscopy Basics.
When light of a fixed wavelength impinges upon a material, it may be absorbed and re-emitted by the material as a spectrum of wavelengths of different intensities. Spectral features result from the transition of electrons among the energy levels of the material, and thus provide quantum mechanical information about the material’s structure and composition. The study of emitted light can provide a powerful characterization method to discover new materials and improve old ones. It can allow a geologist to discover information about the mineral composition of a rock sample, and allow a chemist to determine the chemical composition of a sample.
Spectroscopy is broken down into several categories depending on how light interacts with the material of interest. Some common types of spectroscopy are photoluminescence, Raman, and reflectance. These spectroscopic methods are non-destructive and provide detailed insight, at the quantum level, into the composition and characteristics of the material without having to break, etch, machine, or otherwise destroy the sample. An instrument capable of providing a suite of such measurements to a scientist or engineer can enable major discoveries of new materials, but it can also allow users to get a near-instant answer to the question of whether what they grew, spun, pulled, sputtered, or otherwise produced is what they think it is. Spectroscopic instruments with multiple functions are as valuable to a materials researcher as an oscilloscope is to an electrical engineer.
Microscopy Basics.
Microscopes are instruments used to see objects that are too small to be seen with the naked eye. There are many different types of microscopes that are optimized to “look” at small objects in different ways. Some microscopes use light, others use electrons, while a third type uses a probe to scan across the surface of the sample. These various techniques are optimized to give different information about the sample under study. Klar’s microscope are optical microscopes, since they use light to examine the sample. They use an LED to illuminate the sample and form an image on the camera, and they also use a laser and spectrometer for scanning the sample and capturing the spectrum at each point.
UV Microscopy and Spectroscopy.
Performing measurements using ultraviolet (UV) light gives researchers access to a range of fluorescent molecules and wide band gap semiconductors. In addition, Raman measurements can benefit from UV excitation through increased signal or resonant enhancement. In some cases, the enhancement can be several orders of magnitude. For these and many other reasons, working with UV is attractive. However, the benefits come with a unique set of challenges. This tutorial describes some of the challenges inherent in UV work and mitigation strategies.
