Dave Mitchell's DigitalMicrograph™ Scripting Website

// function to calculate the relatavistic wavelength of electrons

// beamvoltage is in kV, and the wavelength is returned in m and Angstroms

// version:20080229

// D. R. G. Mitchell, adminnospam@dmscripting.com (remove the nospam to make this email address work)

// v1.0, February 2008

number relativisticwavelength(number beamvoltage)

{

beamvoltage=beamvoltage*1000 // it is easier to handle voltages as kV outside the function

number c=2.998e8 // velocity of light

number m=9.1095e-31 // rest mass of electron

number h=6.6261e-34 // Planck's constant

number e=1.6022e-19 // charge on electron

number lambda // relativistically corrected electron wavelength

number scatfact // atomic scattering factor

// calculate the relativistically corrected electron wavelength

lambda=h/sqrt((2*m*beamvoltage*e*(1+(e*beamvoltage)/(2*m*c**2))))

return lambda

}

// Main program starts here

number lambda, beamvoltage, defaultvoltage=200

if(!getnumber("Enter beam voltage /kV",defaultvoltage,beamvoltage)) exit(0)

lambda=relativisticwavelength(beamvoltage)

showalert("Beam Voltage = "+beamvoltage+" kV\n\nWavelength = "+lambda+" m\n\nWavelength = "+lambda/1e-10+" A",2)

Result("\nBeam Voltage = "+beamvoltage+" kV\nWavelength = "+lambda+" m\nWavelength = "+lambda/1e-10+" A\n")