TEM grid preparation Carbon evaporation Various devices are available to hold carbon rods for evaporation. Two 1/8” carbon rods are used, one flat and the other pointed or sharpened into a smaller cylinder, so that it will reach evaporation temperature. Form a 1 mm diameter tip about 1 mm long on a 5 cm carbon rod. Flatten the end of another 5 cm rod with emery paper. the shadow indicator is in place and distances are made correct, place the carbon rods in the tension holders so that the specimens will be in front of the flat rod surfaces (see diagram). At sufficient vacuum (0.2 um Hg) evaporate half the length of the tip. By using the formula for thickness with R=10cm, the following table can be made: Tip length (nm) Thickness (nm) Indication 0.4 2.5 very 0.6 3.8 light 0.8 5.0 medium 1.0 6.2 medium light 2.0 12.5 very dark Note: To carbon stabilize collodion-coated grids on the back, tilt the perforated rack of grids upside down with a toothpick at one end. Pease, 1965, pp. 200-205; Kay,1965, pp. 66-68 Gold evaporation Use R= 10cm and 0.008” wire Wire length (cm) Weight (mg) t (A) Indication 1 5 20 very 2 10 40 light (thin) 4 20 80 medium 6 30 120 medium dark 8 40 160 - 12 60 240 very dark (thick)
TEM grid preparation Carbon evaporation Various devices are available to hold carbon rods for evaporation. Two 1/8” carbon rods are used, one flat and the other pointed or sharpened into a smaller cylinder, so that it will reach evaporation temperature. Form a 1 mm diameter tip about 1 mm long on a 5 cm carbon rod. Flatten the end of another 5 cm rod with emery paper. the shadow indicator is in place and distances are made correct, place the carbon rods in the tension holders so that the specimens will be in front of the flat rod surfaces (see diagram). At sufficient vacuum (0.2 um Hg) evaporate half the length of the tip. By using the formula for thickness with R=10cm, the following table can be made: Tip length (nm) Thickness (nm) Indication 0.4 2.5 very 0.6 3.8 light 0.8 5.0 medium 1.0 6.2 medium light 2.0 12.5 very dark Note: To carbon stabilize collodion-coated grids on the back, tilt the perforated rack of grids upside down with a toothpick at one end. Pease, 1965, pp. 200-205; Kay,1965, pp. 66-68 Gold evaporation Use R= 10cm and 0.008” wire Wire length (cm) Weight (mg) t (A) Indication 1 5 20 very 2 10 40 light (thin) 4 20 80 medium 6 30 120 medium dark 8 40 160 - 12 60 240 very dark (thick)
TEM%20grid%20prep.docx