REFRACTIVE-INDEX AND ABSORPTION-COEFFICIENT AS MEASURES OF STRUCTURAL ORGANIZATION IN CARBONIZED BITUMEN

Microscope photometry has been used to determine reflectances, measured in air and in stable immersion oil, of the carbonized products of the asphaltite bitumen, gilsonite. Comparison of values for parameters (n' and k'), analogous to refractive index and absorption coefficient which are derived from the reflectances, with several X‐ray parameters of the carbonized samples suggests that microscope photometry offers a sensitive alternative method for following changes that take place in the molecular‐structural organization of organic materials during coalification and carbonization processes. Although direct measurement of lattice dimensions is not possible, the optical method is more rapid than X‐ray procedures, is less expensive in terms of capital equipment, while the reflectance measurements can be made on extremely small, discrete and categorically identified field areas, not on the finely ground bulk samples required for X‐ray procedures. Wider application of the microscope photometric method to other carbonized materials and the possibility of absolute correlations between optical and X‐ray data must await more detailed study. The preliminary data are sufficiently encouraging to warrant further extended investigations. 1978 Blackwell Science Ltd