Achieve #12

[lilyhoke 2E]

I have been working on problem 12 of the achieve homework, which states:

The electron affinity of thulium has been measured by a technique known as laser photodetachment electron spectroscopy. In
this technique, a gaseous beam of the anions of an element is bombarded with photons from a laser. Electrons from the anion are
then ejected and their energies are detected. The incident radiation had a wavelength of 1064 nm, and the ejected electrons were
found to have an energy of 0.137 eV. The electron affinity is the difference in energy between the incident photons and the
energy of the ejected electrons. Determine the electron affinity of thulium in units of electron volts per.

I have been unable to solve for the first portion of the question, and I'm not sure where I'm messing up. I'm using the equation given for finding the energy of the incident radiation, converting it to joules, then subtracting the ejected electron energy from that. Are these the right steps to be taken?

[Arnav Ranade 2K]

I took the same steps to solve it. I converted the wavelength of the incident radiation to frequency and then frequency to Joules using e=hv. Then converted the energy of electrons from eV to J. Then I subtracted one from the other. Did you convert back from Joules to eV at the end? That's the reason I got it wrong the first time.

[sambrown12]

I used Planck's constant in order to get the energy of incident photons. Then using that value I calculated the electron affinity by using (Planck's constant x speed of light)/wavelength - 0.137 eV. This was able to get me the electron affinity.