Extending this to Hydrogen Results from solving the Shrodinger equation for the hydrogen atom Z is the atomic number m e is the mass of an electron e is the charge of an electron or proton ID: 539714
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Slide1Slide2
Emission/Absorption SpectraSlide3
Extending this to HydrogenResults from solving the
Shrodinger equation for the hydrogen atomZ is the atomic numberme is the mass of an electrone is the charge of an electron or proton
h is Planks constantr is atomic radiuse0 is the permittivity of free space
Agrees with experimental resultsConstants combined= Rydberg constantSlide4
Rydberg Equation: DerivationIf the energy of a given energy level is defined as E
n=-Rh(1/n2). We can find the difference in energy shells by Enf-Eni
Either of these are often shown in text books. Use whichever you prefer but be sure not to mix them up. One has a negative one does not.
Change= Final
-
initialSlide5
Rydberg ExampleI’ll do: The energy levels of hydrogen-like one-electrons of atomic number Z differ from those of hydrogen by a factor of Z
2. Predict the wavelength of the transition from n=2 to n=1 in He+. (1.17)Slide6
Rydberg ExampleA violet line is observed at 434 nm in the spectrum of atomic hydrogen. Determine the values of n for the beginning and ending energy levels of the electron during the emission of energy that leads to this spectral line (1.16).
Hints:We are observing a line, therefore is a photon being absorbed or emitted?
Based on the answer to the above: is the final higher or lower than the initial? What does that mean about DEThe Balmer series is the hydrogen emission series that is in the visible region what does this mean about
nf? (homework you could look up, on an exam I’d tell you). Please type your answer into your
iclickerSlide7
Extending to other atoms:If we have all one type of atom, and we excite all of them to a particular energy level, what will be true of the emitted light?
The photons will all have the same wavelengthThe photons have different wavelengthsNo photons will be emittedThe photons will have different energies
I do not know Slide8
Reflected vs. Emitted
Emitted light comes from a particular source. Examples?Reflected light “bounces” off other objects Examples? Each time we think about light think about which it belongs too.Slide9
Lasers
Light Amplification by Stimulated Emission of Radiation.
http://www.infoplease.com/images/ESCI112LASERS003.gif
Why can’t we see the laser light until it hits the wall?
Slide10
Transitional Example ProblemIf a bag of potato chips has 1000 calories and 100 chips, how many calories are there per chip?How did you did you do that?
Now if a laser pulse has 1 J Total and 1000 Photons how many joules per photon?Make an Equation using these two questions relating total energy to energy of a photon. Slide11
Example Problem:A monochromatic beam of light with a total energy of 2.5J contains 8.56x10
-4 mols of photons. What is the wavelength of the beam? Slide12
What do we use Emission Spectra for?
Hydrogen Emission Spectra
Fe Emission Spectra
Given the above, and furthermore, that elements have specific emission spectra, what could we use spectroscopy of elements for?Slide13
What do we use Emission Spectra for?
Emission Spectra is unique to individual elementsSpectra can be collected and matched to known emission spectra to determine the element present. Flame tests
Hydrogen Emission Spectra
Fe Emission Spectra
Flame testSlide14
Emission Spectra: Applications in Astronomy
Spectra is collected
Compared to known ionsTemperatures knownSlide15
Time to regress to our 5 yr old selvesWhy is the grass green
?Slide16
The grass is green because…
What happens if you shine green light on the plants?
What happens if you shine red light on the plants?
chlorophyll absorbs red light and reflects green light
eyes see
reflected
green lightSlide17
Time to regress to our 5 yr old selvesWhy
is the sky blue?Slide18
Why is the Sky Blue?Slide19
Time to regress to our 5 yr old selvesWhy is the Sun Yellow/Orange?
(hint: is it really?)Slide20
Why is the sun yellow/orangeSlide21
Spectroscopy
microscopyU
**don’t memorize thisSlide22
Green Fluorescent Protein (GFP)
Tsien
Anthony Chan, Emory University