Fig. 7

Average long-axis radius of TMV estimated from their distribution in AFM images. Particles were identified using the Otsu’s method when TMV was deposited on HOPG (a, b) or mica (c). AFM data have been acquired on unexposed samples (control), after a standard exposure as well as after 30 min exposure (over-exposed). Upon increasing exposure time in X-ray beam, a consistent decrease in the long-axis radius of TMV is observed which corresponds to a fragmentation of TMV particles upon radiation damage. The number of identified particles on HOPG 10 μm was 3912, 2273 and 354 for over-exposed, standard exposure and control, respectively; on HOPG 5 μm the number of identified particles was 1906, 68 and 33 for over-exposed, standard exposure and control, respectively; on mica the number of identified particles was 347, 157 and 304 for over-exposed, standard exposure and control, respectively