8.5 Atomic Spectra and X-rays

X-rays are produced by bombarding a metal target with high-energy electrons. If the target is replaced by another with two times the atomic number, what happens to the frequency of X-rays?

Atomic and molecular spectra are discrete. What does discrete mean, and how are discrete spectra related to the quantization of energy and electron orbits in atoms and molecules?

NGC1763 is an emission nebula in the Large Magellanic Cloud just outside our Milky Way Galaxy. Ultraviolet light from hot stars ionize the hydrogen atoms in the nebula. As protons and electrons recombine, light in the visible range is emitted. Compare the energies of the photons involved in these two transitions.

How do the allowed orbits for electrons in atoms differ from the allowed orbits for planets around the sun?

What is the minimum frequency of a photon required to ionize: (a) a $\text{He}^{+}$ ion in its ground state? (b) A $\text{Li}^{\text{2}+}$ ion in its first excited state?

The red light emitted by a ruby laser has a wavelength of 694.3 nm. What is the difference in energy between the initial state and final state corresponding to the emission of the light?

Estimate the wavelength of the $K_{\alpha}$ X-ray from calcium.

X-rays are produced by striking a target with a beam of electrons. Prior to striking the target, the electrons are accelerated by an electric field through a potential energy difference:

$\Delta U = − e \Delta V ,$

where e is the charge of an electron and $\Delta V$ is the voltage difference. If $\Delta V = 15,000$ volts, what is the minimum wavelength of the emitted radiation?

Suppose the experiment in the preceding problem is conducted with muons. What happens to the minimum wavelength?

A color television tube generates some X-rays when its electron beam strikes the screen. What is the shortest wavelength of these X-rays, if a 30.0-kV potential is used to accelerate the electrons? (Note that TVs have shielding to prevent these X-rays from exposing viewers.)

The maximum characteristic X-ray photon energy comes from the capture of a free electron into a K shell vacancy. What is this photon energy in keV for tungsten, assuming that the free electron has no initial kinetic energy?

Compare the X-ray photon wavelengths for copper and gold.