Comprehensive notes for Chapter 20 Atomic Spectra. Covers Atomic Spectra types, Bohr's Model of Hydrogen Atom, X-rays production and properties, and Lasers (He-Ne).
Continuous Spectrum: Continuous range of frequencies (e.g., Black body).
Line Spectrum: Discrete lines characteristic of an element (e.g., Atomic Hydrogen).
Spectral Series of Hydrogen:
$$ R_H = 1.0974 \times 10^7 m^{-1} $$
Postulates: 1. Circular orbits without radiating. 2. Angular momentum quantization $$ mvr = \frac{nh}{2\pi} $$. 3. Energy emission/absorption on transition $$ hf = E_n - E_p $$.
Radius: $$ r_n = n^2 r_1 $$ where $$ r_1 = 0.53 \mathring{A} $$.
Energy: $$ E_n = -\frac{E_0}{n^2} $$ where $$ E_0 = 13.6 eV $$.
X-rays: High frequency EM radiation ($$ \lambda \approx 10^{-10} m $$). Produced by reverse photoelectric effect.
Characteristic X-rays: Due to inner shell transitions. $$ K_{\alpha} $$ (L to K), $$ K_{\beta} $$ (M to K). Energy depends on target material.
Continuous X-rays (Bremsstrahlung): Due to deceleration of electrons hitting the target. Min wavelength $$ \lambda_{min} = \frac{hc}{Ve} $$.
LASER: Light Amplification by Stimulated Emission of Radiation.
Principle: 1. Population Inversion (More atoms in excited state). 2. Stimulated Emission (Incident photon triggers emission of identical photon). 3. Metastable State (Longer lifetime $$ 10^{-3} s $$).
He-Ne Laser: Most common gas laser. Neon provides laser action (Red light $$ 632.8 nm $$).