R₂₁ (sec⁻¹)

Stimulated emission rate coefficient for transition from level 2 to 1 [24]

R₂₆ (sec⁻¹)

Stimulated emission rate coefficient for transition from level 2 to 6 [32]

K_EP

Energy pooling collisions [11]

K_mn (cm³ sec⁻¹)

Electron-atom collisional excitation or de-excitation between the states m and n [17]

K_nc (cm³ sec⁻¹)

Electron collisional ionization rate coefficient from any energy level (n) [6]

K_RD (cm³ sec⁻¹)

Radiative recombination rate coefficient to any energy level (n) [33]

K_cn (cm⁶ sec⁻¹)

Three body recombination rate coefficient [33]

A₂₁, A_nm (n > m)

Einstein coefficient for the spontaneous emission from the resonance level (2 → 1) and transition from any level n > m (n → m) [34]

K_AI1 and K_AI2,

Associative ionization for the reactions (3p-3p) [15] , and (3p-3d) [16]

K_MHI

Hornbeck-Molnar ionization [35]

K_PI

Penning ionization [29]

${\sigma }_{nc}^{\left(1\right)}$

Single-photon ionization cross section from any high energy level n [36]

${\sigma }_{2c}^{\left(2\right)}$

Two-photon ionization cross section from the saturated energy level (3P) [36]

${\sigma }_{\text{PL}}$

Laser-induced Penning ionization cross section [20]

$K_{4d+{\text{Na}}_2}$

Triatomic associative ionization rate coefficient [1]