[3dem] lambda

Ramanathan Natesh r.natesh at mail.cryst.bbk.ac.uk
Thu Nov 15 10:17:43 PST 2007

Hi All,

    Could anyone point me to a reference or show me how do we get from
classical formula for wavelength

lambda  = h/sqrt(2meV)    to   lambda = 12.398/sqrt[kV*(1022+kV)]

that is used in SPIDER glossary 

m=mass 9.11 x 10^-31 Kg;  e=electron charge 1.6 x 10^-19 C 
h= 6.62 x 10^-34 J*sec V=voltage in volts
kV=kilo Volts.

    eg: for 120 kV  I get lambda = 0.03539 using classic formula but
                    I get lambda = 0.03349 from formula in SPIDER 
glossary.   Though the variation in 3rd decimal may/may not be 

thanks in advance,

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