UPSC Combined Geo-Scientist, Mains · 2021 · Mains Paper III
Q1(f). Why the ICP is an important source for emission spectroscopy
Question
“Inductively Coupled Plasma (ICP) source is important as an atomisation source for emission spectroscopy.” Explain why.
Answer in brief
The argon plasma is at 6000–10 000 K, far hotter than any flame, and chemically inert; atomisation is complete, chemical interference almost disappears, and many elements are determined together at very low concentrations.
Key points
- Very high temperature, 6000–10 000 K: even refractory compounds dissociate, so chemical interference is essentially eliminated.
- Efficient excitation of about 70 elements, non-metals included: low detection limits.
- Inert argon, long residence time, electron-rich plasma: no oxide formation, small ionisation interference.
- Optically thin emitting zone: little self-absorption, calibration linear over about 4 to 6 orders of magnitude.
- One set of conditions excites all elements: simultaneous multi-element analysis.
The full model answer
As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.
CoversICP-OESinductively coupled plasmaargon plasmaatomic emission spectroscopy
All parts of Question 1
- 1(a) Q-test on four results for cadmium in dust5 marks
- 1(b) Ultimate analysis of coal5 marks
- 1(c) Molar absorptivity from the transmittance5 marks
- 1(d) Gravimetric estimation of zinc in brass5 marks
- 1(e) Requirements of an extracting solvent5 marks
- 1(f) Why the ICP is an important source for emission spectroscopy5 marks
- 1(g) Hollow-cathode lamp: function and working5 marks
- 1(h) Powder X-ray diffraction for identifying solids5 marks