Hi, could someone help me with Achieve HW question #12. The question is:
"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 atom."
Not quite sure what to do. Thank you!
Achieve HW Q12
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Re: Achieve HW Q12
It sounds like "electron affinity" is just another way to say work function. We solve this by finding the energy put onto the thulium by using the 1064 nm wavelength. Determine the associated frequency, and then the energy from the radiation. If we were given the ejected electrons' energy in joules, we would subtract the joules from the wavelength by the given value. However, the ejected electrons have 0.137 eV, so before we subtract, we need to convert J to eV. There are 1.602 x 10-19 J per eV. After converting, subtract the incident radiation and the energy of the ejected electrons to find the electron affinity.
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Re: Achieve HW Q12
Hello! I did #12 with my TA in office hours. I'll attach my work and try to walk you through my steps as well.
1. convert 1 ev to Joules : 1 ev = 1.6 x 10^-19J & nm to m : 1064 nm = 1.064 x 10^-6 m
2. Use the equation E=hc/v : E = 6.626 x 10^34 (3 x 10^8) / 1.064 x 10^-6 --> E=1.87 x 10^-19J
3. convert your energy in J to ev : 1.87 x 10^-19J = 1.169 ev
4. find the difference between incident and ejected energy : 1.169ev-0.137ev = 1.032 electron affinity
part 2
5. convert ev to atoms using Avogardo's Constant: 99.43 atoms
1. convert 1 ev to Joules : 1 ev = 1.6 x 10^-19J & nm to m : 1064 nm = 1.064 x 10^-6 m
2. Use the equation E=hc/v : E = 6.626 x 10^34 (3 x 10^8) / 1.064 x 10^-6 --> E=1.87 x 10^-19J
3. convert your energy in J to ev : 1.87 x 10^-19J = 1.169 ev
4. find the difference between incident and ejected energy : 1.169ev-0.137ev = 1.032 electron affinity
part 2
5. convert ev to atoms using Avogardo's Constant: 99.43 atoms
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