Calculates cross section for a electron-Hydrogen impact excitation transition from
the state to the state at energy eb
Type | Intent | Optional | Attributes | Name | ||
---|---|---|---|---|---|---|
real(kind=Float64), | intent(in) | :: | eb | Collision energy [keV] |
Cross Section []
function e_excit_1_4_janev(eb) result(sigma)
!+Calculates cross section for a electron-Hydrogen impact excitation transition from
!+the \(n=1\) state to the \(m=4\) state at energy `eb`
!+
!+###Equation
!+$$ e + H(1) \rightarrow e + H(4) $$
!+
!+###References
!+* Eq. 5 and Table 2 in Ref. 2 [[atomic_tables(module)]]
!+
real(Float64), intent(in) :: eb
!+ Collision energy [keV]
real(Float64) :: sigma
!+ Cross Section [\(cm^2\)]
real(Float64), parameter :: sigma0 = 5.984d0
real(Float64), parameter :: deltaE = 12.75d0
!+ Fitting parameter from Table 2 in Ref. 2
real(Float64), parameter :: alpha = 0.41844d0
!+ Fitting parameter from Table 2 in Ref. 2
real(Float64), dimension(5), parameter :: A = [ 0.24300d0, 0.24846d0, &
0.19701d0, 0.d0, &
0.d0 ]
!+ Fitting parameters from Table 2 in Ref. 2
real(Float64) :: ecoll, x, s
ecoll = eb*1.d3
x=ecoll/deltaE
s = A(2) + A(3)/x + A(4)/x**2.0 + A(5)/x**3.0
sigma = 1.d-16 * sigma0/(deltaE*x) * (1.0 - 1.0/x)**alpha * (A(1)*log(x) + s)
if(x.le.1.0) sigma = 0.d0
end function e_excit_1_4_janev