Spectral lamps radiate line spectra of various gases and metal vapors with high brightness and spectral purity. Spectral lamps are used in conjunction with narrow bandpass filters for applications where monochromatic light is necessary to conduct experiments, such as in spectroscopy and chemistry.
Spectral lamps are commonly used as a light source in scientific, research, and laboratory applications because they produce the high quality, stable monochromatic light useful for determining spectral lines. Spectral lamps use two glass chambers: one contains the pressurized metal vapor and the other is the overall glass tube that encloses both the electrical apparatus and the pressurized tube, connecting everything to the base of the lamp. Spectral lamps are electric discharge lamps, using an electric charge that reacts with the gas, usually mercury or thallium vapor, in the pressurized chamber to produce light. Because the metal vapor is under pressure, a spectral lamp must be constructed of quartz tubing. The quartz tubing also contains a set of tungsten wire electrodes at either end of the tube that are used to ignite the vapor.
Spectral lamps give off a very intense light and some actually generate ultraviolet (UV) radiation. Operators are protected from UV radiation by closed lamp housings and special cooling grids on the lamp. While in operation, spectral lamps also generate very high internal pressures. Spectral lamps come with a base design called a Pico 9 and must be used in lamp holders that properly fit the base. With the right adapters, however, spectral lamps can also be operated in older model lamp holders.
Spectral lamps are used in spectroscopic applications to set a reference point for the spectrometer. Using a spectral lamp as a reference or calibration lamp involves mounting the lamp on the opposite side of the spectrometer from the detector. In this position, the spectral calibration lamp produces two spectral lines that fall on the detector. These lines are further calibrated by using a slit to produce lines that correspond to specific widths. These emissions are used to test the detector and track any measurement discrepancies.