Methods to overcome preferred orientation in cryo-samples for single particle analysis

A method for reducing a preferred orientation of particles in a cryo-sample includes receiving the cryo-sample in a vacuum chamber, depositing amorphous ice onto the cryo-sample while the cryo-sample is in the vacuum chamber, delivering an energy pulse to the cryo-sample in the vacuum chamber to temporarily melt the amorphous ice on the cryo-sample to liquid water to promote movement of the particles in the cryo-sample to a changed orientation different from the preferred orientation, and allowing the liquid water to revitrify to amorphous ice upon cessation of the energy pulse to fix or trap the particles in the cryo-sample in the changed orientation.