Deuterium lamps

A distinction must be made between continuous sources (hydrogen or deuterium lamps, incandescent tungsten lamps, high pressure xenon lamps) and spectral line sources (mercury lamps), which deliver spectrally purer light in the region of their emission lines. 

Continuous sources The sources of choice for measurements in the ultraviolet spectral region are hydrogen or deuterium lamps [1]. When the gas pressure is 30 to 60 X10 Pa they yield a continuous emission spectrum. The maxima of their radiation emission occur at different wavelengths (Hi A = 280 nm Di 2 = 220 nm). This means that the deuterium lamp is superior for measurements in the lower UV region (Fig. 15). 

Fig. 15 Relative intensity distribution of the radiation produced by a hydrogen and a deuterium lamp.

R = recorder, I = integrator, E = detector, Pr = sample (TLC plate), S = mirror, M = monochromator, L = lamps (incandescent lamp , deuterium lamp 0 and mercury lamp G), FI = cutoff filter. 

However, the optical train illustrated in Figure 22B allows the determination of fluorescence quenching. The interfering effect described above now becomes the major effect and determines the result obtained. For this purpose the deuterium lamp is replaced by a mercury vapor lamp, whose short-wavelength emission line (2 = 254 nm) excites the luminescence indicator in the layer. Since the radiation intensity is now much greater than was the case for the deuterium lamp, the fluorescence emitted by the indicator is also much more intense and is, thus, readily measured. 

In these instruments the monochromated beam of radiation, from tungsten and deuterium lamp sources, is divided into two identical beams, one of which passes through the reference cell and the other through the sample cell. The signal for the absorption of the contents of the reference cell is automatically subtracted from that from the sample cell giving a net signal corresponding to the absorption for the components in the sample solution. 

Phillips 4025 Deuterium lamp Tungsten lamp (accessory) 190-380 190-600 0.005-1.28 (9 ranges) 10 4 at 230 nm... 

Variable-wavelength detector, showing deuterium lamp, optical path, reference photodiode and monochromator. 

Fig. 1. Schematic of PAF-V. Key DM, drive motor SA, screw assembly RSA, reactant solution A RSB, reactant solution B DS, drive syringes SV, main switching valves PD, photodetector WB, water bath WA, waste FO, focusing optics M, monochrometer RS, receiving syringe DL, deuterium lamp TL, tungsten lamp ACS, adjustable cell support C, mixing/observation cell W, quartz windows A, reactant A entrance to cell B, reactant B entrance to cell E, product exit from cell RCS, rigid cell support T, a portion of the 4.6 m of coiled tubing not shown for clarity. Reproduced from Ref. (1) by permission of the Royal Society of Chemistry.

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... 

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