Gains Tutorial

Gains Tutorial

Andy Therrien

Uncorrected Image

Ni/Cu alloy

CO dose and 120 K anneal

Atomic Resolution

80 K Image

Uncorrected Image

5 Deg off horizontal

Measure across 39 Cu atoms

X Component:Cos(5) = X/H

Actual: H = 9.6509 nmX = 9.614 nm

Theoretical:H = 0.256 x 39 = 9.984 nmX = 9.946

X Correction:9.946/9.614 = 1.035

Adjacent = X

Hypotenuse

Uncorrected Image

0.5 Deg off vertical(more evidence that there is an angle error in raw image)

Measure across 31 root 3 Cu spacings

Y Correction:Cos(0.5) = A/H

Actual: A = 9.6395 nmH = 9.639 nm

Theoretical:A = (√3)0.256 x 31 = 13.746 nmH = 13.745

Y Correction:13.745/9.639 = 1.426

Adjacent = Y

Hypotenuse

Apply the Gains

Measure over 10 atoms in each close packed direction(so each should be 2.56 nm)

2.5896 nm (1.2% error)

2.4173 nm (5.6% error)

2.7272 nm (6.5% error)

The one we calibrated for is really good but the other two are off

Unit Cell Detection

Software tells you what to do

In dialog box select oblique

Set your angle to 60 (or 120 depending of unit cell)

Set La and Lb to whatever you made your unit cell(so this is 7 by 8 atoms so its 1.792 by 2.048)

Hit apply and make sure the correction factors at the bottom are reasonable

Apply the Gains

Measure over 10 atoms in each close packed direction

2.6016 nm (1.6% error)

2.5194 nm (1.6 % error)

2.5350 nm (1.0% error)

All of them are pretty good, if you want to improve more do it again!