Abstract
This practice describes the photomultiplier properties that are essential to their judicious selection and use of in emission and absorption spectrometry. The properties covered here include structural features, electrical properties, and characteristics involved in precautions and problems. The structural features covered are envelope configurations, window materials, electrical connections, and housing for the external structure, and the photocathode, dynodes and anode, and rigidness of structural components for the internal structure. Electrical properties, on the other hand, incorporate the following: optical-electronic characteristics of the photocathode including spectral response; current amplification including gain per stage, overall gain, gain control (voltage-divider bridge), linearity of response, and anode saturation; signal nature; dark current including cathode size, internal aperture, and refrigeration effects; noise nature including additivity of noise power, signal-to-noise ratio, equivalent noise input; and photomultiplier properties as a component in an electrical circuit including output impedance, response time, and signal gating and integration possibilities. Finally, the characteristics involved in precautions and problems cover fatigue and hysteresis effects, illumination of photocathode, and gas leakage.
Scope
1.1 This practice covers photomultiplier properties that are essential to their judicious selection and use in emission and absorption spectrometry. Descriptions of these properties can be found in the following sections:
Section
Structural Features
4
General
4.1
External Structure
4.2
Internal Structure
4.3
Electrical Properties
5
General
5.1
Optical-Electronic Characteristics of the Photocathode
5.2
Current Amplification
5.3
Signal Nature
5.4
Dark Current
5.5
Noise Nature
5.6
Photomultiplier as a Component in an Electrical Circuit
5.7
Precautions and Problems
6
General
6.1
Fatigue and Hysteresis Effects
6.2
Illumination of Photocathode
6.3
Gas Leakage
6.4
Recommendations on Important Selection Criteria
7
1.2 Radiation in the frequency range common to analytical emission and absorption spectrometry is detected by photomultipliers presently to the exclusion of most other transducers. Detection limits, analytical sensitivity, and accuracy depend on the characteristics of these current-amplifying detectors as well as other factors in the system.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
