ReflectION.for

      SUBROUTINE REFLECTION(TT,TNT,FMOLE)
      INCLUDE 'Soldiv.fi'
      PARAMETER (NH = 5)
      DIMENSION RN(NH,NH)
C     CALCULATES ATOMIC REFLECTION AND MOLECULAR RE-EMISSION FRACTIONS
C     FOR NEUTRAL OR ION AT TEMPERATURE TT--1-FMOLE AND FMOLE--AND TEMP
C     OF REFLECTED NEUTRAL ATOM (AFTER DISSOCIATION)--TNT
c     atomic/molecular split on reflection
      IF(IMOL.EQ.0) GOTO 150
      IF(TT.GE.TINT(2).AND.TT.LT.TINT(3)) IN = 2
      IF(TT.GE.TINT(3).AND.TT.LE.TINT(4)) IN = 3
      IF(TT.GT.TINT(4)) GOTO 10
      IF(TT.LT.TINT(2)) GOTO 15
      EMOL = 2.0
C      NEUTRAL ATOM REFLECTION COEFICIENTS @ 1, 10 AND 100 eV
C           (POP,2,3740,1995)
C     ACTUALLY TABULATE & INTERPOLATE 1 - RN
C           BERYLLIUM
      RN(1,2) = 0.82
      RN(1,3) = 0.82
      RN(1,4) = 0.91
C           CARBON
      RN(2,2) = 0.67
      RN(2,3) = 0.67
      RN(2,4) = 0.82
C           TUNGSTEN
      RN(3,2) = 0.24
      RN(3,3) = 0.24
      RN(3,4) = 0.40

C           TEMPERATURE INTERPOLATION

      W = LOG10(RN(IMAT,IN)) + LOG10(RN(IMAT,IN+1)/RN(IMAT,IN))*
     2    LOG10(TT/TINT(IN))/LOG10(TINT(IN+1)/TINT(IN))
      FMOLE = 10.**W
      RNNE = 1. - FMOLE
      GOTO 20
C     USE THE 100 eV RE-EMISSION COEF FOR T > 100 eV
 10   FMOLE = RN(IMAT,4)
      RNNE = 1. - FMOLE
      IF(IMOL.EQ.0) GOTO 150

      GOTO 20
C     USE THE 1 eV RE-EMISSION COEF FOR T < 1 eV
 15   FMOLE = RN(IMAT,2)
      RNNE = 1. - FMOLE

 20   CONTINUE
      GOTO 200
 150  FMOLE = 0.0
      RNNE = 1. - FMOLE

 200  TNT = (0.5*(1.-FMOL)*TT + FMOL*EMOL)

      RETURN
      END