Lineare Silizium-Photodioden-Matrizen mit parallelem Datenausgang als Strahlungsempfänger in der optischen Emissionsspektroskopie—I. Messanordnung und Analysen mit Funkenstrahlungsquelle

A linear silicon photodiode array has been used which consists of 5 photodiodes each having a separate output. Because of the dimensions of a single photodiode, i.e. 3mm long and 20 μm wide, they are capable of replacing the exit slits of a spectrometer. The read out system having 3 channels is described in detail. In each channel a FET operational amplifier with a low input bias current served as a current-to-voltage converter.The signal-to-noise ratios of systems using the photodiode array and of a photomultiplier (EMI 9789 QB) respectively are compared. The dynamic range of the photodiode is linear and extends over 5 $\text{1}\text{2}$ decades referred to the noise level. As an analytical example copper was determined in aluminium alloys using medium voltage spark excitation in an argon atmosphere. The limit of detection was c = 4.8 × 10^?3%, the relative standard deviation as a measure of the precision was s_rel = 0.014 for concentrations above 0.08%.In part II the application of recently produced photodiode arrays on the analysis of powders with a glow discharge will be described.