SUBROUTINE LIQCH4(WAVELN,XNR,XNI)
*
* /DATA FROM MARTONCHIK AND ORTON, 1994, Vol 33, no 36. Applied Optics/
*   Table 2, (90 K)
*
      DIMENSION W(44),XN(44),XK(44)
      DATA W/
     &1000.00,  71.4300, 41.6700,  8.2600,  8.1300,  7.8000,  7.6900,
     &  7.5900,  3.5700,  3.4300,  3.3700,  3.3300,  3.2900,  1.9530,  
     &  1.9320,  1.2410,  1.2350,  1.0140,  1.0000,  0.9872,  0.9742,  
     &  0.8885,  0.8673,  0.8418,  0.7994,  0.7849,  0.7299,  0.7174,  
     &  0.7057,  0.6856,  0.6696,  0.6215,  0.5983,  0.5831,  0.4000,  
     &  0.1337,  0.1200,  0.1162,  0.1087,  0.1012,  0.1000,  0.0900,  
     &  0.0545,  0.0020/
      DATA XN/
     &  1.2930,  1.2910,  1.2900,  1.3310,  1.3250,  1.3650,  1.2750,
     &  1.1950,  1.3030,  1.3000,  1.3100,  1.2780,  1.2420,  1.2850, 
     &  1.2850,  1.2860,  1.2860,  1.2870,  1.2870,  1.2870,  1.2870,
     &  1.2880,  1.2880,  1.2880,  1.2880,  1.2890,  1.2890,  1.2890,
     &  1.2890,  1.2900,  1.2900,  1.2910,  1.2910,  1.2910,  1.2990,
     &  1.7030,  1.4860,  1.4710,  1.5080,  1.4450,  1.4480,  1.2090, 
     &  0.8560,  1.0000/
      DATA XK/
     &5.302e-05, 1.442e-03, 6.645e-04, 1.067e-02, 2.135e-02, 7.994e-02, 
     &1.706e-02, 7.728e-02, 1.066e-02, 2.132e-02, 4.264e-02, 7.462e-02,
     &3.198e-02, 8.947e-07, 1.574e-06, 8.425e-08, 1.677e-07, 1.000e-06, 
     &8.313e-07, 6.281e-07, 4.958e-07, 1.899e-06, 3.311e-07, 4.998e-08,
     &6.103e-08, 3.995e-08, 9.907e-08, 1.156e-07, 8.381e-09, 2.675e-09, 
     &4.771e-09, 1.951e-07, 1.167e-09, 1.237e-09, 1.000e-10, 1.814e-01, 
     &3.336e-01, 3.225e-01, 3.761e-01, 4.768e-01, 4.853e-01, 6.501e-01, 
     &2.137e-01, 1.137e-01/  
      XNR=XN(1)
      XNI=XK(1)
      IF (WAVELN .GT. W(1))  RETURN
      XNR=XN(44)
      XNI=XK(44)
      IF (WAVELN .LT. W(44)) RETURN
      DO 100 I=2,44
      IF (WAVELN .GT. W(I) ) GO TO 101
 100  CONTINUE
 101  CONTINUE
C ALL INTERPOLATION IS IN LOG LAMBDA
      FACTOR= (alog(WAVELN) - alog(W(I)) ) / (alog(W(I-1)) - alog(W(I)))
C REAL PART IS LINEARLY INTERPOLATED
      XNR=XN(I) + FACTOR*(XN(I-1) - XN(I))
C IMAGINARY PART IS LOG INTERPOLATED
      XNI=alog(XK(I)) + FACTOR*(alog(XK(I-1)) - alog(XK(I)))
      XNI=exp(XNI)
          iF(XNI.lt.1.e-7) XNI=1.e-7
      RETURN
      END