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_2_janev(eb) result(sigma)
!+Calculates cross section for a electron-Hydrogen impact excitation transition from
!+the \(n=1\) state to the \(m=2\) state at energy `eb`
!+
!+###Equation
!+$$ e + H(1) \rightarrow e + H(2) $$
!+
!+###References
!+* Eq. 4 and Table 1 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=10.2d0
real(Float64), parameter :: a=0.228d0
!+ Fitting parameter from Table 2 in Ref. 2
real(Float64), parameter :: b=0.1865d0
!+ Fitting paramter from Table 2 in Ref. 2
real(Float64), parameter :: c=0.5025d0
!+ Fitting paramter from Table 2 in Ref. 2
real(Float64), dimension(6), parameter :: An = [ 4.4979d0, 1.4182d0, &
-20.877d0, 49.735d0, &
-46.249d0, 17.442d0 ]
!+ Fitting parameters from Table 2 in Ref. 2
real(Float64) :: ecoll, x, s
ecoll = eb*1.d3
x = (ecoll)/deltaE
if((ecoll.gt.10.2).and.(ecoll.le.11.56)) then
sigma = 1.d-16 * (a + b*(ecoll - deltaE))
return
endif
if((ecoll.ge.11.56).and.(ecoll.le.12.23)) then
sigma = 1.d-16 * c
return
endif
if(ecoll.ge.12.23) then
s = An(2) + An(3)/x + An(4)/x**2.0 + An(5)/x**3.0 + An(6)/x**4.0
sigma = 1.d-16 * sigma0/(deltaE*x) * (An(1)*log(x) + s)
return
endif
if(x.le.1.0) then
sigma = 0.0
return
endif
end function e_excit_1_2_janev