Deep-Dive Guides · Inorganic Spectroscopy

Inorganic Spectroscopy & Characterisation — the complete deep dive

A single guide dense enough to take you from "I know the technique's name" to CSIR-NET Part-C mastery.

Free extract — the opening section of the guide, in full.

0. How to use this guide — the technique map

Before any single technique, fix the map. Every characterisation problem is really asking one of a small number of questions about the molecule. The table tells you which technique answers which question, so in a Part-C problem you can reach for the right tool immediately:

Question about the compound	Best technique(s)	Physical quantity measured	Diagnostic output
Geometry / symmetry (cis vs trans, fac vs mer, Td vs D_4h)	IR & Raman (band counting)	Vibrational normal modes (change in dipole / polarizability)	Number of IR- and Raman-active ν(CO) bands
Centre of symmetry present?	IR + Raman together	Mutual exclusion rule	No band is both IR- and Raman-active
Oxidation state / d-electron count	UV–vis (d–d), Mössbauer (δ), XPS	Ligand-field transitions; s-electron density	Transition energies (Δ_o); isomer shift
Spin state (high- vs low-spin)	Magnetic moment, EPR, Mössbauer	Unpaired electrons; EFG	μ_eff; quadrupole splitting; δ
Ligand field strength / covalency	UV–vis (Racah B)	d–d transition energies	Δ_o, nephelauxetic ratio β
Coordination number / local structure	NMR, IR band counting, EXAFS	Chemical shift, coupling, symmetry	Multiplicity, satellites, band count
Fluxionality / dynamics	Variable-temperature NMR	Exchange rate vs NMR timescale	Coalescence / averaged environments
Molecular formula / nuclearity	Mass spectrometry (ESI/MALDI)	m/z of ions & fragments	Isotope envelope, M⁺ pattern

The three questions to ask of any spectrum: (1) What physical quantity is being measured (a dipole change? an s-electron density? a magnetic resonance?)? (2) What selection rule decides whether a feature appears (IR/Raman activity, Laporte, spin, 2I+1)? (3) What structural conclusion does the number/position/intensity of features force? Answer these and you can reason out band counts and assignments from scratch — which is exactly what Part-C rewards One caveat about the map: three of the entries — magnetic moment (μeff), XPS and EXAFS — are listed only so that you recognise when they are the right tool. They are not developed anywhere below; the techniques this guide actually works through are IR/Raman, UV–vis, EPR, Mössbauer, multinuclear NMR and mass spectrometry.

Read the rest of this guide

The remaining 10 sections — Vibrational spectroscopy — IR & Raman, Electronic spectra — d–d transitions & UV–vis, EPR — electron paramagnetic resonance, Mössbauer spectroscopy and more — are part of ChemVidya Full Access, along with the other guides, the books, the study notes and 6,000+ practice questions with worked solutions.

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