The removal of surface-adhered nanoparticles on the AS
value influenced the CDF value measurement. The AS values ofboth the types of silica particles increased by performing
ultrasonic cleaning over the surface. The AS value of porous
silica was not remarkable since the amount of surface-adhered
nanoparticles on porous silica was less than nonporous fused
silica (FB-6S), as shown in Fig. 2(a) and (c).