Beer-Lambert Law
X-ray attenuation follows the exponential decay law:
I(x) = I₀ × exp(-μ × x)
Where μ is the total linear attenuation coefficient (cm⁻¹), combining photoelectric absorption and scattering contributions.
Interaction Cross-Sections
Data from NIST XCOM database. The total mass attenuation coefficient includes:
- Photoelectric: Dominant at low energies (< 30 keV)
- Compton: Dominant at medium energies (30-100 keV)
- Rayleigh: Coherent elastic scattering
Radiolysis G-Values
Radiation chemical yields expressed as molecules per 100 eV of absorbed energy:
| Species | G-Value | Reference |
|---|---|---|
| OH• (hydroxyl) | 2.7 | Buxton et al., 1988 |
| e⁻aq (solvated electron) | 2.6 | Buxton et al., 1988 |
| H• (hydrogen atom) | 0.6 | Buxton et al., 1988 |
| H₂O₂ | 0.7 | Buxton et al., 1988 |
| H₂ | 0.45 | Buxton et al., 1988 |
| HO₂• | 0.02 | Spinks & Woods, 1990 |
Compton Scattering Energy
The Klein-Nishina formula describes the angular distribution of scattered photons:
E' = E / (1 + (E/511)(1 - cosθ))
Where E is incident energy (keV), E' is scattered energy, and θ is scattering angle.
X-ray photon
Photoelectric absorption
Compton scatter
OH• radical
e⁻aq
Model Validation Against Published Data
Validation References
- NIST XCOM: Photon Cross-Sections Database (Berger et al.)
- Buxton et al., 1988: Critical review of rate constants for reactions of hydrated electrons
- Spinks & Woods, 1990: Introduction to Radiation Chemistry
- Hubbell & Seltzer, 1995: NIST Standard Reference Database 126