Optical spectroscopy is a branch of physics that studies the interaction of light with matter. Its aim is to obtain an optical spectrum, i.e. the dependence of the intensity of radiation absorbed, reflected, emitted or scattered by a substance on the wavelength, from which the properties of the material under study can be deduced.
Supercontinuum lasers output white light with a spectral width similar to conventional lamps, but with the properties of a laser beam. This combination ("as wide as a lamp and as bright as a laser") makes them a popular alternative to classical broad-spectrum light sources such as xenon and deuterium lamps and halogen lamps.
The FLIM (Fluorescence Lifetime Imaging Microscopy) method uses an optical microscope to image the lifetime of fluorescence. It is a fluorescence microscopy technique that uses fluorescence to create contrast in individual microscopic images. The output is a so-called FLIM map, which gives the spatial distribution of the fluorescence lifetime for a selected region of the sample. The FLIM setup can be implemented by combining an optical microscope with a TCSPC luminescence spectrometer.
Raman microspectrometry at low temperatures (4K) and a unique configuration of a closed-cycle optical cryostat and microscope objective to achieve high numerical apertures.
The Raman effect is the inelastic scattering of light on particles (molecules and atoms) in which the particles transition to one of the quantum states by transferring a quantum of energy. Raman spectroscopy is a very efficient and non-destructive technique that provides information about vibrational and rotational transitions in molecules. It is used in many applications, including basic research, routine process control and materials identification.
Time-Correlated Single Photon Counting (TCPC) is a very sensitive method that allows the measurement of time-resolved fluorescence with a temporal resolution on the order of picoseconds (ps) to nanoseconds (ns). It is a digital technique based on the statistical nature of the quenching of luminescent photons.
In monochromators, stray light is defined as unwanted signal that passes through the monochromator together with the desired (set) spectral band. Modern monochromators have an automatic carousel with filters to remove higher diffraction orders. They also use high quality, low scattering optical elements. In addition, the parasitic signal can be significantly suppressed by using a dual monochromator.
Two-dimensional excitation-emission spectra are becoming an increasingly desirable output in the study of photoluminescent materials. To obtain a complete excitation-emission map (EEM = Excitation-Emission Map), the excitation wavelength must be systematically varied and the emission spectrum recorded for each individual setting. Using a fast CCD detector, the EEM can be obtained in a very short time.
Plasmonic cavities are an effective tool for improving optical processes in nanoscale materials. Tightly confined optical fields at junctions between metal nanoparticles can lead to an increase in local light intensity by up to several orders of magnitude. This allows surface-enhanced Raman scattering, surface-enhanced infrared absorption, strong coupling and the Purcell effect - spontaneous enhancement of light emission.
Today, colour measurement and comparison is mainly used for quick and easy quality control of individual products (change in whiteness of clothing fabrics, colour of foodstuffs, consistency of light sources in commercial lighting, comparison of different batches). Modular colour measurement kits can be easily adapted to a wide range of sample types.
The study of absorption, luminescence, transmittance, reflection and scattering of optical radiation is one of the most common spectroscopic measurements. They allow information about the substance under study to be obtained efficiently and non-destructively. It is therefore not surprising that they are constantly being improved and renewed.
The measurement of lifetime, or quenching, is a typical example of how the study of the temporal evolution of optical properties (time-resolved spectroscopy) helps us to identify and describe the microscopic processes occurring in the materials under investigation.