Pluto via New HorizonsInfrared Spectra show water-iceCourse AnnouncementsAssignmentsQuiz 2 ResultsBrief recap of last timeBrief recap of last timeSpectrum of HydrogenHydrogen Energy DiagramSpectrum of HydrogenExample Hydrogen Lines QuestionExample Hydrogen Lines QuestionKirchhoff’s Laws ExplainedUnderstanding Kirchhoff’s LawsUnderstanding Kirchhoff’s LawsUnderstanding Kirchhoff’s LawsUnderstanding Kirchhoff’s LawsAtoms heavier than HydrogenAtoms heavier than HydrogenSpectrum of an Emission NebulaMolecular LinesMolecular LinesMolecular LinesSpectral Line AnalysisSpectral ThermometerRadial VelocityLine BroadeningThermal Broadening - TemperatureCollisional/Pressure BroadeningRotational BroadeningMagnetic Field BroadeningPluto via New HorizonsCredit: NASA/JHUIAPL/SwRIInfrared Spectra show water-iceCredit: NASA/JHUIAPL/SwRIPure water ice onlyWater Ice Nitrogen IceMethane Ice CO IceCourse Announcements•Quiz 2 graded –Last Names starting with A – M in front of class–Last Names starting with N – Z in back of class•Exam 1 will take place Wednesday, 28 Sept.–Will cover Chapters 1 – 4–Will release study materials throughout the week. •Mastering Astronomy Exam 1 Study Guide now available–Study sessions next Monday and Tuesday evenings (combined with A151)•A151 Primary - Monday Night at 5:30 PM – Physics 304•A152 Primary – Tuesday Night at 5:30 PM – Physics 304AssignmentsReading Assignments•Chapter 5. Sections 5.1, 5.2, and 5.4[Read by Friday, 23 Sept.]Parallel Lectures•No new parallel lecturesMastering Astronomy•Chapter 4 Homework[Due Monday, 26 Sept. at 11:59 PM EDT]Quiz 2 ResultsEstimated Difficulty: Moderate (on the hard end)Mean: 7.1Median: 7.5Standard Deviation: 1.98Most missed questions:•Red Light versus Green Light? Which is faster?•Recognizing Newton’s 2nd Law (F = ma or a = F/m). The acceleration an object experiences is related to the force exerted on the object and the mass of the object.•Kepler’s 3rd Law: P2 [in years] = a3 [in AU]•Wein’s Law: The peak wavelength is inversely proportional to the temperature of an object.–1/3 as hot => lower temp., therefore longer peak wavelengthGiven that the comparison object peaks at 4 µm, this means that the 1/3 as hot object will peak at 4 µm × 3 = 12 µmBrief recap of last timeThe important bits to understand how light interacts with matter (the field of spectroscopy)•Light comes in discrete packets of energy (quanta), which is carried by an elementary particle called a photon. –Energy of a photon is dependent on the wavelength–That is, a photon of a specific wavelength has a very exact amount of energy.•In an atom, the electrons ‘orbit’ the nucleus at very specific distances, and cannot be in-between these very specific distances.–Where the electron can be is called an orbital.–The electron needs to have the exact energy of that orbital to be in that orbital. No other energy will do.–The lowest energy orbital is where electrons like to be. This is orbital is called the ground state.–An electron can ‘jump’ between orbitals only if it absorbs the exact amount of energy required to go into a ‘higher’ (further from the nucleus) orbital, or if it gives up (emits) the exact amount of energy to ‘fall’ into a ‘lower’ (closer to the nucleus and the ground state).Brief recap of last timeThe important bits to understand how light interacts with matter (the field of spectroscopy)•The energy required for the electron’s ‘jumps’ and ‘falls’ between different orbitals comes in the form of light packets, photons.–If a photon has the exact right amount of energy (the right wavelength) that corresponds to the energy need for an electron to jump to a higher, excited state, then that atom will absorb that wavelength (color) of light.–Electrons will naturally make their way back to their lowest energy state (toward the ground state). For them to ‘fall’ from one orbital to another, they must shed the extra energy they have (the lower state is lower energy). •If that electron gains energy from a photon and jumps to an excited state, we say the atom has absorbed the photon.•If the electron falls to a lower energy orbital (lower excited state or ground state), it releases the energy as a photon with energy equal to the energy difference between the two orbitals. Here, we say the atom has emitted a photon.Spectrum of HydrogenSpectral SeriesLyman SeriesTransitions starting or ending at the Ground State (n =1)-Ultraviolet Lines-Lα = 121.6 nmBalmer SeriesTransitions starting or ending at the 1st Excited State (n =2)-Visible Lines-Hα = 656.3 nmHydrogen Energy DiagramSpectral SeriesLyman SeriesUltraviolet (UV)PhotonsBalmer SeriesVisible LightPhotonsSpectrum of HydrogenThe Balmer Series – Visible Light Emission/AbsorptionHydrogen Alpha - HαHydrogen Beta - Hβ Hγ HδA spectrum of an element gives us a view of the energy structure of that element’s electron energy levelsExample Hydrogen Lines QuestionThe Balmer Series line, Hydrogen Alpha, will be seen as an absorption line when the electron in the hydrogen atom makes which electronic transition?A. 1st Excited State to Ground State (n = 2 -> 1)B. Ground State to 1st Excited State (n = 1 -> 2)C. 2nd Excited State to Ground State (n = 3 -> 1)D. Ground State to 2nd Excited State (n = 1 -> 3)E. 2nd Excited State to 1st Excited State (n=3-> 2)F. 1st Excited State to 2nd Excited State (n=2-> 3)Example Hydrogen Lines QuestionThe Balmer Series line, Hydrogen Alpha, will be seen as an absorption line when the electron in the hydrogen atom makes which electronic transition?A. 1st Excited State to Ground State (n = 2 -> 1)B. Ground State to 1st Excited State (n = 1 -> 2)C. 2nd Excited State to Ground State (n = 3 -> 1)D. Ground State to 2nd Excited State (n = 1 -> 3)E. 2nd Excited State to 1st Excited State (n=3-> 2)F. 1st Excited State to 2nd Excited State (n=2-> 3)EmissionEmissionEmissionAbsorptionAbsorptionAbsorptionKirchhoff’s Laws ExplainedHydrogen Gas CloudUnderstanding Kirchhoff’s Laws•Continuous spectral source (the bulb) emits all wavelengths of light•Now imagine that continuous spectrum interacts with a cooler gas cloud full of atomsHow continuous, emission, and absorption spectra relateUnderstanding Kirchhoff’s Laws•Certain energies of light (wavelengths) are absorbed by the atoms in the gas–Occurs at the specific energies of light (wavelengths) that correspond to
View Full Document
Unlocking...