Spectroscopic Measurement

A spectroscopic measurement is the process of determining the wavelength(s) of light emitted or absorbed by a material. The most common type of spectroscopy is absorption spectroscopy, in which light that has passed through a sample is analyzed to determine what fraction was absorbed at each wavelength. Emission spectroscopy, in which light emitted by a sample is analyzed, can also be used to determine composition. In both cases, the results are typically presented as a graph of absorbance or emission vs. wavelength ( often called a “spectrum”).

The first step in performing a spectroscopic measurement is to choose the appropriate instrument for the task at hand. There are many different types of spectrophotometers available on the market, each with its own advantages and disadvantages. The choice of instrument will depend on factors such as the type and concentration of samples being measured, the required accuracy and precision of the measurements, and the budget available for purchasing equipment.

Once an instrument has been selected, it must be calibrated to ensure accurate results. This usually involves using standards with known concentrations (or absorptivities) and measuring their absorbance (or emission) at various wavelengths. The calibration curve generated from these measurements can then be used to convert unknown concentrations into absorbances (or emissions).

After calibration is complete, samples can be measured and their absorbances (or emissions) graphed as a function of wavelength. If Absorbance vs Wavelength data are being collected, then Beer’s Law may be used to quantitatively analyze the results and determine concentrations. Alternatively, if Qualitative Measurements are desired ,then spectral linescanning can be performed to identify individual compounds present in a sample mixture based on their characteristic absorption/emission patterns .