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#UV spectrum

2 public questions tagged with this topic.

Ultraviolet, X-rays, Gamma Rays and Their Properties

What is the approximate wavelength range of ultraviolet rays as per the document?

**Ultraviolet** λ≈10-400 nm, produced by atomic transitions and Sun, causes fluorescence, sterilization, harmful to eyes/skin, absorbed by ozone layer. **X-rays** λ≈10⁻² to 10 nm, produced by rapid deceleration of energetic electrons in X-ray tube, used in medicine for diagnosis (shadow of bones) and cancer therapy due to high ionization and penetration, detected by photographic film and Geiger counter. The document states that ultraviolet rays range from about 400 nm to 0.6 nm . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields 400 nm to 0.6 nm,

Ref: NCERT > Physics Book > Electromagnetic Waves > Ultraviolet, X-rays, Gamma Rays and Their Properties

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UV-VIS spectroscopy

Which transition has energy < 210 nm?

Photon energy inversely proportional to wavelength, so shorter wavelength means higher energy. In carbonyls, amides and heteroaromatics, forbidden n→π* transition promotes lone pair electron to antibonding π* orbital, requiring relatively low energy and appearing at longer wavelengths around 270-300 nm, beyond 210 nm threshold. Therefore energy associated with 210 nm photon exceeds that needed for n→π*, placing n→π* on low-energy side of spectrum, distinct from high-energy σ→σ* below 150 nm. Understanding this ordering helps assign absorption bands, predict solvent effects and rationalize phot

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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