An interferometer provides an alternative approach for wavelength selection. Instead of filtering or dispersing the electromagnetic radiation, an interferometer allows source radiation of all wavelengths to reach the detector simultaneously, as illustrated […]
An absorption filter has one significant limitation—because a filter has a fixed nominal wavelength, if you need to make measurements at two different wavelengths, then you need to use two different filters. A […]
The simplest method for isolating a narrow band of radiation is to use an absorption filter, which work by selectively absorbing radiation from one or more regions of the electromagnetic spectrum. A […]
In Nessler’s original colorimetric method for ammonia, developed in the 1850s before the advent of spectrophotometers, the sample and several standard solutions of ammonia are placed in separate tall, flat-bottomed tubes. As […]
A source of electromagnetic radiation must provide an output that is both intense and stable. Sources of electromagnetic radiation are classified as either continuum or line sources. A continuum source emits radiation […]
The illustration here is a simplified energy diagram showing the absorption and emission of a photon by an atom or a molecule. When a photon of energy hν strikes the atom or molecule, […]
Illustration of plane-polarized electromagnetic radiation showing the oscillating electric field in red and the oscillating magnetic field in blue. The radiation’s amplitude, A, and its wavelength, λ, are shown. Normally, electromagnetic radiation […]
