Detector, atomic spectrometer linearity

ICP-AES is a technique of measurement used for the detection and determination of elements with the aid of atomic emission. The solution for measurement is atomized and the aerosol is transported into an inductively coupled plasma (ICP) with the aid of a carrier gas. There, the elements are excited such that they emit radiation. This is spectrally dispersed in a spectrometer and the intensities of the emitted element lines are measured by means of detectors (photomultipliers). A quantitative statement is possible by means of calibration with reference solutions, there being a linear relationship between the intensities of the emission lines and the concentrations of the elements over a broad range (usually several powers of ten). The elements may be determined either simultaneously or consecutively. 

Inductively coupled plasma-mass spectrometry is one of the most sensitive techniques available for trace analysis. Analyte ions produced in the plasma are directed into the inlet of a mass spectrometer, which separates ions by their mass-to-charge ratio. Ions are measured with a sensitive detector that is similar to a photomultiplier tube. The linear range listed in Table 20-4 extends over eight orders of magnitude, and the detection limit is 100-1 000 times lower than that of furnace atomic absorption. 

Figure 23.14 Schematic of double-molecular beam apparatus. Counter-propagating laser beams intersect pulsed molecular beams the pump (photolysis) beam produces atomic Cl that expands outwards and crosses the R H molecular beam. The HCl product is state-selectively photoionized by the probe laser using (2 + 1) REMPI. The resulting ions are detected with a 2D position-sensitive imaging detector after passage through a linear TOF mass spectrometer. Reproduced from Toomes and Kitsopoulos, Phys. Chem. Chem. Phys., 2003, 5 2481, with permission of the PCCP Owner Societies...

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