Thermal desorption results of HCOOH from gold surface. Panels a and b: desorption rates of HCOOH for m/z 47 and m/z 46 on gold surface; panel c: integrated areas below the TPD curves of HCOOH for m/z 47 and m/z 46 as a function of the HCOOH exposure time on gold surface; and panel d: surface population of HCOOH as a function of the desorption energy of HCOOH from gold surface for m/z 46. The desorption energy distribution E_i (in kJ mol⁻¹) and the surface population N_i (in ML) are derived from the desorption rate Eq. (4) with the best-fit pre-exponential factor A = 1 × 10¹⁸ s⁻¹. Figure in the inset shows the best fit of the TPD data (m/z 46) of HCOOH on gold surface for an exposure dose .