Radiation chemistry — IUPAC Division I physical chemistry at the ionizing-radiation / radiolysis grain. Foundations: (1) Radiation chemical yield G(X) = number of molecules of species X formed per 100 eV of energy deposited (historical…
radiation-chemistry
G-value: yield per 100 eV; charge balance G(e_aq⁻)=G(H₃O⁺)
The radiation chemical yield G(X) is the central quantitative concept in radiation chemistry: G(X) = (molecules of X formed) per (100 eV of…
Spur-track structure: LET scaling ρ_track ∝ LET; α/γ ≈ 2000/3
Spur theory (Samuel & Magee 1953, Mozumder-Magee 1966) partitions the primary radiation track into localised radical clusters of…
e_aq⁻ pseudo-first-order: [e](t) = [e₀]·exp(−k[S]t); t_½ = ln 2/k_eff
Hydrated-electron (e_aq⁻) kinetics (Hart & Boag 1962; Anbar, Bambenek & Ross, NSRDS-NBS 43 compiled rate constants). The hydrated electron…
Charge balance: G(e_aq⁻) − G(H₃O⁺) = 0 (identity under substitution)
Sympy-exact witness of the charge-conservation identity in water radiolysis. Setup: define G_bal(G_e, G_H3O) = G_e − G_H3O as the…
LET ratio: ρ_α / ρ_γ = LET_α / LET_γ = 200 / (3/10) = 2000/3 exact
Sympy-exact witness of the α / γ LET ratio using sp.Rational arithmetic. Setup: LET_α = 200 (keV/μm, representative for 5-MeV α…
e_aq⁻ half-life at k_eff=1: t_½ = log(2); concentration halves exactly
Sympy-exact witness of the pseudo-first-order half-life identity on the hydrated electron. Setup: [e_aq⁻](t) = e₀·exp(−k_eff·t) where…
Bateman decay-chain framework: N₁ → N₂ → stable with N₂(t) = (λ₁/(λ₂−λ₁))·N₁(0)·(e^(−λ₁t) − e^(−λ₂t))
The Bateman 1910 solution for a two-member radioactive decay chain N_1 → N_2 → stable: N_1(t) = N_1(0)·e^(−λ₁t); N_2(t) =…
Rutherford scattering framework: dσ/dΩ = (Z_p·Z_t·e²)²/(16·E²·sin⁴(θ/2))
Rutherford 1911 scattering cross-section for a charged projectile of charge Z_p·e_q scattering off a heavy nucleus of charge Z_t·e_q: dσ/dΩ…
Lindhard-Scharff low-velocity electronic-stopping framework: dE/dx ∝ Z_p^(1/6)·v in the v ≪ v₀·Z_p^(2/3) regime
Lindhard-Scharff 1961 low-velocity electronic stopping power: for an ion of velocity v ≪ v_0·Z_p^(2/3) (v_0 = Bohr velocity) the…
Bateman secular equilibrium: N₂/N₁ = λ₁/λ₂, A₁ = A₂, dN₂/dt = 0 at t ≫ 1/λ₂ with λ₁ ≪ λ₂
At secular equilibrium: dN₂/dt = λ₁N₁ − λ₂N₂ = 0, giving N₂/N₁ = λ₁/λ₂ and A₁/A₂ = 1. Canonical pins: ratio lambda_1/lambda_2, activity…
Rutherford cross-section: σ(π) = Z²Z²e⁴/(16E²); σ(π/2) = Z²Z²e⁴/(4E²); ratio σ(π/2)/σ(π) = 4
Angular-ratio fingerprint: σ(π/2)/σ(π) = sin⁴(π/2)/sin⁴(π/4) = 1/(1/4) = 4. Canonical pins: cross-section at θ=π (backscatter,…
Lindhard low-v scaling: dE/dx ∝ v (linear); doubling v doubles stopping; scaling Z by 64 doubles stopping (64^(1/6) = 2)
Linear-velocity scaling fingerprint: doubling v doubles stopping power (factor 2); scaling Z by 64 doubles stopping power (64^(1/6) = 2). …
G-value (Fricke dosimetry)
Fricke 1927 ferrous-sulfate dosimeter G(Fe3+) = 15.5 +/- 0.4 per 100 eV gamma; primary standard radiation-chem dosimetry; reference G_OH =…
Water radiolysis
Spinks-Woods 1960s water radiolysis: H2O -> e_aq, OH, H, H2, H2O2, H3O+; e_aq absorption 720 nm; basis of nuclear-reactor +…
Pulse radiolysis (Keene 1964)
J Keene 1964 + Hart-Boag 1962 ns-electron pulse + transient-absorption; e_aq direct observation; basis of ns-radical kinetics measurement.
Track structure (Onsager 1938)
L Onsager 1938 ion-pair recombination + escape probability; modern Magee-Chatterjee ion-track diffusion-kinetic-model; basis of…
Oxygen effect (OER)
Gray 1953 OER ~3 for X-rays vs 1 for high-LET; oxygen fixes radical-induced damage; basis of hypoxic-tumor radio-resistance +…
Radiation grafting
Chapiro 1955 + Charlesby 1956 radiation-induced grafting + crosslinking; PE-radiation crosslinking commercial cable insulation; LDPE 1958…
Fricke dosimeter (1929)
H Fricke 1929 ferrous-sulfate radiation-dosimeter; modern alanine-EPR + thermoluminescence-dosimeter + radioprotector design.
Actinium (Debierne 1908)
A Debierne 1899-1908 actinium discovery; modern Z=89-95 + 225Ac-PSMA-617 prostate-cancer + targeted-α-therapy 2018+.
Water radiolysis (Spinks 1990)
Spinks-Woods 1990 'Introduction to Radiation Chemistry'; modern e-aq scavenging + nuclear-power-plant + space-radiation tissue.
Track structure (Magee 1964)
J Magee-A Mozumder 1964 track-structure spurs / blobs / short-tracks; modern Monte-Carlo Geant4-DNA radiobiology.
Radiosensitizer (Adams 1973)
G Adams-D Cooke 1973 radiosensitizer-misonidazole hypoxic-cell; modern modern nimorazole 2024 head-and-neck + carbogen breathing.
X-ray therapy (Röntgen 1895)
W Röntgen 1895 (Nobel 1901) X-rays + Coolidge tube 1913 + linac 1953; modern proton + carbon-ion + FLASH-RT.
Hart-Boag spectroscopic identification of the hydrated electron e^-_aq
Hart-Boag identification (Hart-Boag 1962 *J Am Chem Soc* 84, 4090) is the first direct spectroscopic detection of the hydrated electron…