The samples of substrates after SSF were studied by infrared (IR)
spectroscopy. All samples were dried at 60 ◦C, then ground in a coffee
grinder to homogenise and 100 mg of powder was ground in a
Specamill (SPECAC, USA) to the particle size of 1 m. Powdered, dry
samples (7–10 mg) and 1 g of dried KBr were ground to homogenize
and pelted.