1. Spectroscopy and Stationary States

2. Spectroscopy
Prism
Single Slit
Diffraction: Bending of light as it passes between areas of different optical density
Incandescent Light Bulb
Continuous Spectrum (5 colors shown for clarity)
“White Light” Source

3. Hydrogen Spectroscopy
+ HIGH VOLTAGE
- HIGH VOLTAGE
Prism
Single Slit
Hydrogen Glow Discharge Tube
656.3 nm
486.1 nm
434.0 nm
Why Not A Continuous Spectrum???
410.1 nm
Hydrogen Line Emission Spectrum
Emission Spectra: Bright lines of color separated by regions of total darkness.

4. Spectroscopy Why not the same lines as hydrogen??? Single Slit Prism
Helium Glow Discharge Tube
Helium Line Emission Spectrum
Emission Spectra: Bright lines of color separated by regions of total darkness.

5. Line Spectrum: Identifying a Pattern
Johannes Rydberg (1845 – 1919)
Rydberg Equation:
n12 1 (
n22 1 ) 1  = R -
R: Rydberg Constant.
R =  107 m-1
...n1 and n2 are integers
Found a mathematical pattern in the hydrogen emission line spectrum.
...n2 > n1.

6. Rydberg Equation: Hydrogen Atom
Calculate the wavelength in nanometers of the line having n1=2 and n2=4.
Rydberg Equation:
For Hydrogen Visible Spectrum: 1  R -
n12 (
n22 ) =
n1 = 2
n2 = 3, 4, 5, 6, etc 22 1 ( 42 1 ) 1  = -
 107m-1 1  =
 107m-1
 (0.1875) 1  =
m-1  =
10-7m
= nm