| Process | EEX: Excitation |
| Data type | cross section | uploaded on 2023-02-08 |
| Comment | Fit function and data were taken from Johnson et al. Equation (29). Errors: E<40eV -> 80%, 40eV<E<100eV -> 40%, E>100eV -> 20%. |
| Method | semi-empirical |
| Columns |
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| Threshold | 13.222 eV |
| Ref |
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| Data | Download (data from fit) |
| Fit Function Details |
\[\begin{align*} \sigma_{ex}^{n>2 \rightarrow m>n}(E) &= \frac{1.76 \times 10^{-16}A_1^2I}{A_2E} \Bigg[ 1 - e^{-A_3A_2 \frac{E}{I}} \Bigg] \\ & \Bigg[A_4 \bigg(\ln\bigg(\frac{E}{I}\bigg) + \frac{I}{2E}\bigg) + \bigg(A_5 - A_4\ln\frac{2A_1^2}{A_2}\bigg)\bigg(1 - \frac{I}{E} \bigg) \Bigg] \end{align*}\] | ||||||||||||||
| Python | def h_eex_johnson(E, A1, A2, A3, A4, A5, I):
"""
This function calculates electron impact excitation cross sections (in cm2) of
H n > 2 to m > n , with exception of n=2 to n=3.
param E: requested electron-impact energy in eV
type E: float, np.ndarray
param Ai: fit coefficient
type Ai: float
param I: threshold energy in eV
type I: float
"""
sigma = 1.76e-16*A1**2/(A3*E/I)*(1-np.exp(-1*A3*A4*E/I)) * (A5*(np.log(E/I)+1/(2*E/I)) +
(A6-A5 * np.log(2*A1**2/A3))*(1-1/(E/I)))
return sigma |
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| Fit Precision | 0.6 % | ||||||||||||||
| Fit Coefficients |
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| x-range | 13.461002004468718 – |