with thermal expansion coefficient α, Young's modulus E, tensile pre-stress σ0, and thermal conductivity κ, of the string material. With A being the product of string width and string thickness, the relative frequency change becomes directly proportional to fiber length, and inversely proportional to string width. In other words; the resonator is expected to be more sensitive for long and narrow fibers, the same geometrical prerequisites as for efficient sampling.
In this study, sampling experiments demonstrate the importance of resonator dimensions and aerosol velocity, and show that efficient material deposition can be achieved in a few minutes using inertial impaction sampling. The relationship between resonator geometry and sensitivity is illustrated by measurements of resonance frequency shifts of strings of varying widths and lengths subjected to a fixed laser power change. Finally, two examples of how NAM-IR can be employed for chemical analysis of ENMs are given.