If light is a particle, what is wavelength / frequency ?

[nonequilibrium]

If light is a particle, what is "wavelength"/"frequency"?

Hello,

Is the wavelength of a particle simply the wavelength of the psi-function before measurement? Or (/and?) is it an intrinsic property that is "even there in the particle" when you measure the presence of the particle (i.e. reduction), like energy?

Or is the nature of this question exhibiting a deeper misunderstanding of mine?

My formal knowledge about QM doesn't extend beyond an introductory course.

 

[xts]

Is the wavelength of a particle simply the wavelength of the psi-function before measurement?

Yes. Deeper question: what's the wavelength of particle? DeBroigle wave? - that is exactly the same. EM-wave for photon? - counterparts regarding different (QM / wave optics) approaches

Or is the nature of this question...

Probably "and" not "or"