125379 DR diffuse reflectance 98 886668 DRS diffuse reflectance 29 3601917 DRIFT diffuse reflectance 10 3903716 DRIFTS diffuse reflectance 7 384726 Rd diffuse reflectance 6 114362 DF diffuse reflectance 2 108091 DA diffuse reflectance 1 857703 DFR diffuse reflectance 1