Patent GB-1148664-A (GB)
Title: An atomic absorption spectrophotometer
IPC: H01J17/06
Filed: 1966-05-27
Abstract: 1,148,664. Photo-electric absorportion analysis. AUSTRALIA, COMMONWEALTH SCIENTIFIC & INDUSTRIAL RESEARCH ORGANIZATION. May 27, 1966 [May 28, 1965], No.23995/66. Heading G1A. In a light absorption investigation to determine the concentration of one or more elements in a sample radiation containing the resonance wavelengths of the element(s) to be detected is passed both through an atomic gas or vapour of the sample, which absorbs radiation at the resonance wavelengths of the elements present, and through a resonance lamp containing an atomic vapour or gas of the element(s) which gas will absorb radiation at the resonance wavelengths and re-emit it in all directions; a photo-detector is positioned to receive this re-emitted radiation and provides a signal indicative of the absorption of the resonance wavelength(s) in the sample atomic vapour or gas and hence the concentration of the element(s). The re-emitted resonance radiation of different elements is distinguished by the use of filters infront of one or more photo-detectors. The atomic vapour or gas is produced by introducing a solution or dispersion of the sample into a flame, and may be positioned, in the radiation path, either infront of or behind the resonance lamp. The spectral lamp producing the radiation for transmission through the vapours may be a discharge type and if more than one element is to be detected either separate lamps or a multi-element. lamp produce the individual resonance wavelengths. The resonance lamp producing an atomic vapour of the elements to be detected may be either a discharge lamp or the heated element type Fig. 5 (not shown). For detection of more than one element the individual atomic vapours may be contained within a single resonance lamp or in separate resonance lamps arranged one behind the other in the radiation path. The photo-detectors, may be of the photo-conductive, photo-emmissive or semi-conductor type. The radiation from the spectral lamp may be modulated, either by an optical chopper or by modulating the electrical supply to the lamp, in order to distinguish it from unwanted radiation. 1,148, 665. Photo-electric absorption analysis. AUSTRALIA, COMMONWEALTH SCIENTIFIC & INDUSTRIAL RESEARCH ORGANIZATION. May 27, 1966 [May 28, 1965], No.23996/66. Heading G1A. To determine the concentration of substances dissolved or suspended in a liquid sample by absorption of light at a specific wavelength or the reflectivity of a solid sample at a specific wavelength, light including the specific wavelength is passed through a resonance lamp containing an atomic vapour of an element having a resonance line at the specific wavelength where the specific wavelength is absorbed and re-emitted, possibly along with resonance radiation at other resonance lines of the element, to be received by a photodetector preferably a photo-multiplier; the sample is arranged in the radiation path, either before or after the resonance lamp, and the signal from the detector is indicative of the absorption or reflection at the specific wavelength. Filters may be used so that the detector only receives resonance radiation at the specific wavelength. Reference samples are introduced into the radiation path to calibrate the instrument. Visible, infrared or ultraviolet light may be used. The detection of proteins is described using the thallium resonance line of 2768  or the magnesium line of 2852 . The specific wavelength radiation may be produced by a spectral discharge lamp and the resonance lamp may be either a discharge lamp or a heated element type Fig. 3 (not shown). The spectral lamp and resonance lamp may be contained within a single envelope and multi-element spectral and resonance lamps are envisaged for measurement at more than one specific wavelength. The light from the spectral lamp may be modulated.