Fig. 11

(a) Example of difference between signals recorded at different locations on each bitumen sample for the 6092 nm (1641 cm−1) QCL and (b) the sensing locations on one of the bitumen samples.
(a) Example of difference between signals recorded at different locations on each bitumen sample for the 6092 nm (1641 cm−1) QCL and (b) the sensing locations on one of the bitumen samples.