Heating of an Atomic Force Microscope tip by femtosecond laser pulses

For various applications of nanoscale surface modification by an Atomic Force Microscope, one would like to maintain the AFM tip near the surface and at an accurately controlled elevated temperature. We study the laser heating of an ordinary AFM silicon tip under ambient conditions, and show that a tightly focused laser beam can heat the tip apex to the desired temperature, while affecting the cantilever quite moderately. We demonstrate that the observation of the shift of the silicon Raman line scattered from the tip is an efficient and accurate way to determine the tip temperature, and we substantiate our observations by theoretically modeling the dynamics of heat accumulation in the tip-cantilever system. For situations where Raman measurements are not feasible, we introduce a new method for estimating the tip temperature by monitoring the mechanical resonance frequency shift of the probe.