Contrast and imaging performance in photo induced force microscopy

We numerically analyze PiFM's lateral and vertical (subsurface) imaging performance in the visible and IR regimes. The lateral spatial resolution and subsurface imaging capabilities are limited by the field spatial confinement near the tip apex, which is directly proportional to the excitation wavelength. In addition, we show that near-field optical force exerted on the tip due to sample molecular resonance is indeed in the detectable range....