Ultraviolet light deuterium lamps

A light source used frequently for ultraviolet absorption studies is the deuterium lamp. If an instrument is meant strictly for ultraviolet work, then the deuterium lamp is the only light source present and the instrument is called a UV spectrophotometer. Often, both a tungsten filament lamp and a deuterium lamp are present and are individually selectable. Also, instead of having two independently selectable... 

An ultraviolet detector using a flow cell such as that. in Figure 25-19 is the most common HPLC detector, because many solutes absorb ultraviolet light. Simple systems employ the intense 254-nm emission of a mercury lamp. More versatile instruments have deuterium, xenon, or tungsten lamps and a monochromator, so you can choose the optimum ultraviolet... 

A light source which is usually a tungsten lamp for visible light, a hydrogen or deuterium lamp for ultraviolet light or a quartz-iodide lamp for both regions. 

Compounds which absorb ultraviolet or visible light can be quantified for absorption measurements. Absorption measurements can be obtained in either the reflectance or transmission modes. The instrumentation required for these techniques is shown schematically in Figure 3.13. The vast majority of compounds absorb in the ultraviolet or visible region of the spectrum and deuterium and tungsten lamp sources can be used with prisms or gratings, cheaper instrumentation uses band-pass filters for monochromation. 

Just as the bulb in a table lamp has a finite lifetime, so do the ultraviolet/ visible (UV/Vis) detector lamps (tungsten and deuterium see Chapter 4) in HPLC systems. Light intensity decreases with time due to the evaporation of internal metal components and coatings. Lamps deteriorate with age and use according to most manufacturers, lamps have a lifetime of about 1,000 hours. The lifetime is defined as being the time at which 50% of the light intensity remains. After this time has elapsed, the lamp should be replaced. 

The deuterium halogen lamp is a low pressure gas discharge light source often used in spectroscopy when a full spectrum source of illumination in the ultraviolet region is needed. The origin of the continuum ultraviolet radiation extends from around 160 nm to 400 nm. 

The deuterium arc lamp presents a good continuity and intensity in the ultraviolet region, and a low noise level, but a poor continuity, in the visible range (Fig. 3.6). The intensity of the emitted light of these lamps decreases constantly in time and generally it becomes half of the initial one in circa 1,000 h. 

---