Read what this module is aiming for. Then open the instrument and work through it.
Let's fire a photon at an atom and see what happens.
Tune the photon energy, then fire. Watch the detector.
| Trial | Element | Photon Source energy | KE Detected |
|---|
Fire to log a trial.
What do you notice?
What is the difference between the photon source and the detector? Where did that energy go?
What is the difference between the energy detected when changing atoms, but keeping the photon energy the same? Does that make sense based on what you've learned in the past sections?
Load a sample of the hypothetical atom into the spectrometer, then start the photon source.
The graph under the instrument is a photoelectron spectrum. The horizontal axis is binding energy (ionization energy) in MJ/mol — how tightly each electron was held. The vertical axis is peak height — how many electrons arrived at that energy.
Electrons from this atom only appear at two places on the axis: 0.85 and 4.25 MJ/mol. Nothing in between. Those are quantized energy levels — discrete allowed energies, the same idea as the levels on an energy-level diagram (and on the Bohr-style diagram you may have drawn on paper), without needing orbits.
Peak height tracks how many electrons share each level: 3 at the shallower (valence) energy, 2 at the deeper (core) one. Position tells you the energy; height tells you the count.
The detector measures kinetic energy. Binding energy is what is left.
Photon in, kinetic energy out, binding energy inferred — and peak height counting how many electrons share each quantized level. The full spectrometer — real atoms through neon — comes in the next build.
Try one shot below the energy that ejects an electron, and one well above. What does the detector report each time?
The intentions behind this module, and the competencies you just practised. Read each competency statement and decide honestly how well it fits you right now.