Parameters needed » History » Revision 2
Revision 1 (William Rice, 01/23/2018 02:32 PM) → Revision 2/5 (William Rice, 02/08/2018 03:31 PM)
h1. Parameters needed Need to enter: Checkbox whether to do it at all or not. Slit Width: Suggest to use 15 eV, since calibration was performed at that width. Generally we collect at 20 eV, but there is no problem to switch to 15 eV for the measurement Exposure time: Default is 500 ms, which gives enough signal for the method to work. Can experiment with faster times if desired. Mean free path: We measured mean free path to be 395 nm at NYSBC at 300 kV. It should depend only on the voltage. Collect every N images: Since it adds overhead, you may want to do it only every 5 or 10 images. h1. Objective Scattering Thickness estimate Need to enter Checkbox whether to calculate it or not Exposure Counts over vacuum Mean free path for objective scattering: depends on instrument and aperture diameter. * 300 is a good intitial guess if unknown Values determined at NYSBC: * titan Krios 300 keV 20 eV slit, 100 um objective aperture: 322 nm * titan Krios, 300 keV no EF, 100 um objective aperture: 3329 nm * Tecnai F20 200 keV 100 um objective aperture: 392 nm * Tecnai F20 200 keV 70 um objective aperture: 302 nm * T12 120 keV 100 um objective aperture: 319 nm * T12 120 keV 70 um objective aperture: 247 nm