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David E. Woon & Benjamin J. McCall
Astrochemistry Lecture and Laboratory Courses at the University of Illinois: Applied Spectroscopy David E. Woon & Benjamin J. McCall RH11
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From the UIUC Course Catalog
CHEM/ASTR 450 Astrochemistry Covers the foundations of astrochemistry, a young field at the intersection between chemistry and astronomy. Topics to be discussed include the interstellar medium, atomic and molecular physics, interstellar chemistry, molecular astronomy, and unresolved enigmas in the field. CHEM/ASTR 451 Astrochemistry Laboratory An active, hands-on introduction to observational astrochemistry, laboratory astrochemistry and theoretical astrochemistry. Activities will include astronomical observations of interstellar molecules at the Observatory, spectroscopy of molecules in the laboratory, quantum chemical calculations and simulations of molecular spectra, and modeling of interstellar chemistry.
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History Ben created the two courses and taught them for the first time in Fall 2008 and Spring Development of Chem 450 was supported by NSF CAREER/PECASE Grant CHE Construction of the lab set-up for Chem 451 was supported by an NSF grant from the Course Curriculum and Laboratory Improvement (CCLI) program from DUE (Grant ), which in turn built on Cottrell Scholar Award from the Research Corporation. “Open Your Eyes to the Skies: An Innovative and Interdisciplinary Astronomy/Astrochemistry Teaching Laboratory” (Leslie Looney, Ben McCall, & Nick Glumac) 450: third astrochem lecture; 451: first astrochem lab
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History Ben created the two courses and taught them for the first time in Fall 2008 and Spring Development of Chem 450 was supported by NSF CAREER/PECASE Grant CHE Construction of the lab set-up for Chem 451 was supported by an NSF grant from the Course Curriculum and Laboratory Improvement (CCLI) program from DUE (Grant ), which in turn built on Cottrell Scholar Award from the Research Corporation. “Open Your Eyes to the Skies: An Innovative and Interdisciplinary Astronomy/Astrochemistry Teaching Laboratory” (Leslie Looney, Ben McCall, & Nick Glumac) I taught Chem 451 in Spring 2014 and Chem 450 in Fall 2015.
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Spectroscopic Content
The study of astrochemistry presents an excellent opportunity to highlight the usefulness of spectroscopy for understanding how we know what molecules exist and what they’re doing in exotic astrophysical environments, mostly interstellar clouds but also planetary atmospheres, comets, and stellar atmos-pheres. In particular, the students see the energetic regimes where different types of molecular spectroscopy are relevant, as well as how useful they are for distinguishing one molecule from another.
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Difficulty Warning In both courses, students are warned that the material is not easy and involves a lot of math… Let’s look at each course in sequence.
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Orientation: Basic Astronomy, Resources, Ground Rules
Chem/Astr 450 Astrochemistry FALL 2015 25 Aug 2015 Orientation: Basic Astronomy, Resources, Ground Rules
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Chem/Astr 450 – Astrochemistry Lecture
The course grade was divided into homework sets and a semester-long project on a specific astromolecule. 11 students completed the course in Fall 2015 (9 undergrads & 2 grad students; all from the Chem side). The molecules they studied were: CN CS C2S OH N2H+ CO+ NH3 C2H SiS H2CO C3O Each student built up a wiki entry on their molecule during the semester, which served as the template for an oral presentation and a term paper due at the end of the semester.
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Chem/Astr 450 – Astrochemistry Lecture
The course grade was divided into homework sets and a semester-long project on a specific astromolecule. 11 students completed the course in Fall 2015 (9 undergrads & 2 grad students; all from the Chem side). The molecules they studied were: CN CS C2S OH N2H+ CO+ NH3 C2H SiS H2CO C3O Jacob McAlpin Each student built up a wiki entry on their molecule during the semester, which served as the template for an oral presentation and a term paper due at the end of the semester.
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Astronomy/Astrophysics
Lectures Orientation: Basic Astronomy, Resources, Ground Rules Light & Stars The Interstellar Medium Astronomy/Astrophysics
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Astronomy/Astrophysics
Lectures Orientation: Basic Astronomy, Resources, Ground Rules Light & Stars The Interstellar Medium Interaction of Radiation with Matter (2) Atomic Spectroscopy Molecular Spectroscopy (Diatomics) Molecular Spectroscopy (Polyatomics) (2) Molecular Excitation (2) Astronomy/Astrophysics Spectroscopy
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Astronomy/Astrophysics
Lectures Orientation: Basic Astronomy, Resources, Ground Rules Light & Stars The Interstellar Medium Interaction of Radiation with Matter (2) Atomic Spectroscopy Molecular Spectroscopy (Diatomics) Molecular Spectroscopy (Polyatomics) (2) Molecular Excitation (2) Interstellar Chemistry (3) Kinetic Modeling of Gas-Phase Chemistry Chemical Routes in Diffuse & Dense Molecular Clouds and Disks Miscellaneous Chemistry Astronomy/Astrophysics Spectroscopy Chemistry
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Astronomy/Astrophysics
Lectures Orientation: Basic Astronomy, Resources, Ground Rules Light & Stars The Interstellar Medium Interaction of Radiation with Matter (2) Atomic Spectroscopy Molecular Spectroscopy (Diatomics) Molecular Spectroscopy (Polyatomics) (2) Molecular Excitation (2) Interstellar Chemistry (3) Kinetic Modeling of Gas-Phase Chemistry Chemical Routes in Diffuse & Dense Molecular Clouds and Disks Miscellaneous Chemistry Astronomical Molecular Spectroscopy: Optical Astronomy Astronomical Molecular Spectroscopy: Radio Astronomy Astronomical Molecular Spectroscopy: Interferometry Spectroscopy as a Tool for Astrophysics Astronomy/Astrophysics Spectroscopy Chemistry
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Spectroscopic Topics Covered in Lectures
Einstein coefficients Transition dipole moments Radiative transfer Oscillator strength Optical depth Line widths/broadening Column density Term symbols Electronic spectra Vibrational spectra Rotational spectra Rovibrational spectra Rovibronic spectra Selection rules Line shapes Fine & hyperfine structure Cosmic rays Auger processes Potential energy curves Wigner-Wittmer rules Franck-Condon principle Dipole moments Isotope effects Point groups Using PGOPHER Collisional excitation/deexcitation Photon pumping Formation pumping Recombination n-level system solutions Spectrographs Diffraction gratings/eschelles
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Homework Problems and the Students’ Wikis
Questions spread through the homework sets led the students through the steps of writing the wiki entries for their molecules.
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Homework Problems and the Students’ Wikis
Set 1: Find your astromolecule in the list at the Astrochymist. Initialize the wiki page for your molecule and add a section for the “First Detection.” Include the citation(s) and upload the pdf file(s) for the initial detection(s) as a link.
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Homework Problems and the Students’ Wikis
Set 3: Use ADS or another citation finder to track down subsequent astronomical studies of your astromolecule and add a new subject, “Further Detections,” to your wiki page. Cite 3-5 of the subsequent studies, describe their findings, and explain their importance to the overall story of your astromolecule.
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Homework Problems and the Students’ Wikis
Set 7: This week, you will generate the pure rotational spectrum for your molecule and add it to your wiki page in a section labeled “Spectroscopic Properties and Spectrum.”
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Homework Problems and the Students’ Wikis
Set 7: This week, you will generate the pure rotational spectrum for your molecule and add it to your wiki page in a section labeled “Spectroscopic Properties and Spectrum.”
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Homework Problems and the Students’ Wikis
Set 7: This week, you will generate the pure rotational spectrum for your molecule and add it to your wiki page in a section labeled “Spectroscopic Properties and Spectrum.”
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Homework Problems and the Students’ Wikis
Set 9: Use the KIDA database to identify the most important forma-tion and destruction reactions in the “Reaction Network” for your molecule in a dark cloud such as TMC-1.
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Homework Problems and the Students’ Wikis
Set 9: Use the KIDA database to identify the most important forma-tion and destruction reactions in the “Reaction Network” for your molecule in a dark cloud such as TMC-1.
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Homework Problems and the Students’ Wikis
Set 9: Use the KIDA database to identify the most important forma-tion and destruction reactions in the “Reaction Network” for your molecule in a dark cloud such as TMC-1.
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Homework Problems and the Students’ Wikis
Set 10: Add a “Summary” section to your wiki page that describes your sense of whether the detection of your molecule can be considered robust and how significant it is that your molecule has been detected.
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Astrochemistry Laboratory Methylidyne Radical (CH)
Chem/Astr 451 A/B Astrochemistry Laboratory Spring 2014 Methylidyne Radical (CH) in the Cosmos
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Chem/Astr 451 – Astrochemistry Laboratory
3 credit (A) and 4 credit (B) sections were offered. Chem/Astr 450 was supposed to be a prerequisite, but this was not enforced. Enrollment in section B included three students (1 undergrad, 2 grad students) who had taken 450. Enrollment in section A consisted of 6 undergrads who had not taken 450.
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with the university’s historic 12” refracting telescope
Overview of the Course observe CH with the university’s historic 12” refracting telescope PRIMARY OBJECTIVE OF THE COURSE study CH literature, chemical modeling, quantum chemistry characterize CH with a student-built spectrograph report background, methodologies, laboratory results, astronomical observations techniques data reduction, spectral modeling Labs 1-4 Labs 5-6 Lab 7 Lab 8 (A) Paper (B) 6 weeks 4 weeks 3 weeks ~1-2 weeks individually in groups of 2-3
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A Demanding Course As with 450, I stressed from the beginning that this would not be an easy course. On the theoretical side, they had to learn how to run NAHOON, G09, and IRAF, and they needed to understand LINUX well enough to do so. The spectrograph needed to be aligned and calibrated with standards before it could be used to characterize CH. One of Ben’s students, Brad Gibson, served as course TA and helped the students set up and use the spectrograph.
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The Observatory 12” f/15 Brashear refractor
Assembled in Nov 1896 ($15K) Refurbished in 2013
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The Spectrograph aligned with laser wavelength set with Hg lamp
diffraction grating mirror CCD aligned with laser wavelength set with Hg lamp tested on solar spectrum butane flame used as source of CH table from T. Oka’s lab fiber optic cable 50 fiber “slit” reimaging lens slit
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Results Unfortunately, there has been no successful acquisition of CH spectra to date by students or instructors!
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assumed baseline shown in red*
Venus – corrected and assigned spectrum assumed baseline shown in red*
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assumed baseline shown in red
Sirius – corrected and assigned spectrum assumed baseline shown in red
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Acknowledgment Jacob McAlpin graciously allowed me to use his work in class as an example. He used what he learned in Chem 450 as the starting point for his Organic Chemistry Seminar in Spring 2016.
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