P. Bryan Changala

Center for Astrophysics Harvard & Smithsonian

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Joshua H. Baraban

Ben-Gurion University of the Negev

John F. Stanton

University of Florida

Michael McCarthy

Harvard University

Jun Ye

University of Colorado Boulder

Marie‐Aline Martin‐Drumel

Institut des Sciences Moléculaires d'Orsay

Brett A. McGuire

Massachusetts Institute of Technology

Ryan A. Loomis

National Radio Astronomy Observatory

Bryce Bjork

Honeywell (United States)

Andrew M. Burkhardt

Wellesley College

Ci Xue

Massachusetts Institute of Technology

Cooperative Institutions

University of Colorado Boulder

Centre National de la Recherche Scientifique

National Institute of Standards and Technology

Center for Astrophysics Harvard & Smithsonian

Massachusetts Institute of Technology

Harvard University

Joint Institute for Laboratory Astrophysics

University of Florida

California Institute of Technology

Institut des Sciences Moléculaires d'Orsay

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

EXHAUSTIVE PRODUCT ANALYSIS OF THREE BENZENE DISCHARGES BY MICROWAVE SPECTROSCOPY

Proceedings of the 2022 International Symposium on Molecular Spectroscopy (2020)

Michael McCarthy John F. Stanton James H. Thorpe P. Bryan Changala Jessie Porterfield

10.15278/isms.2020.wi08

Cite

Citations (1)

Resolving High Order Tensor Interactions in C60 Fullerenes

Lee R. Liu D. Rosenberg P. Bryan Changala David J. Nesbitt Timur V. Tscherbul

Laser cooling, trapping, and coherent control of ultracold atoms and molecules has afforded the possibility of assembling pristine and highly tunable quantum many body systems. This relies on excellent experimental control over ultracold atoms or molecules and their interactions. Another paradigm we are exploring is to treat single polyatomic molecules as inherently quantum many body systems due to their strongly interacting constituent nuclei and electrons. In addition, a diverse array of intramolecular coupling mechanisms arise "for free" in polyatomic molecules, such as rovibronic coupling, hyperfine-rotation coupling, covalent bonds between atoms, and nuclear and electron exchange statistics. The key to unlock these phenomena in the lab is quantum-state resolved spectroscopy, which relaxes the requirements for experimental control. However, in general, molecular complexity comes at the price of spectral broadening and congestion. C 60 , with its rigid molecular cage structure and high degree of symmetry, is a notable exception, enabling quantum state resolved spectroscopy in an unusually large polyatomic molecule. We present an experimental rovibrational spectrum of gas phase C 60 fullerene, obtained by QCL (Quantum Cascade Laser) cavity enhanced absorption spectroscopy.

Polyatomic ion

Coherent control

Endohedral fullerene

Coherent spectroscopy

10.1364/quantum.2023.qth4c.7

Cite

Citations (0)

Direct frequency comb measurement of OD + CO → DOCO kinetics

Science (2016)

Bryce Bjork Thinh Bui Oliver H. Heckl P. Bryan Changala B. Spaun

The kinetics of the hydroxyl radical (OH) + carbon monoxide (CO) reaction, which is fundamental to both atmospheric and combustion chemistry, are complex because of the formation of the hydrocarboxyl radical (HOCO) intermediate. Despite extensive studies of this reaction, HOCO has not been observed under thermal reaction conditions. Exploiting the sensitive, broadband, and high-resolution capabilities of time-resolved cavity-enhanced direct frequency comb spectroscopy, we observed deuteroxyl radical (OD) + CO reaction kinetics and detected stabilized trans-DOCO, the deuterated analog of trans-HOCO. By simultaneously measuring the time-dependent concentrations of the trans-DOCO and OD species, we observed unambiguous low-pressure termolecular dependence of the reaction rate coefficients for N2 and CO bath gases. These results confirm the HOCO formation mechanism and quantify its yield.

Hydroxyl radical

10.1126/science.aag1862

Cite

Citations (133)

Data for "Astronomical CH3+ rovibrational assignments"

Zenodo (CERN European Organization for Nuclear Research) (2023)

P. Bryan Changala Ning L. Chen Hai L. Le Bérenger Gans Kim Steenbakkers

Electronic supplementary materials for "Astronomical CH3+ rovibrational assignments" by P. B. Changala et al. https://doi.org/10.1051/0004-6361/202347765 Contents: "Proplyd_MIRI_MRS_stitched_on_off_atomic_cut_baseline_corrected_self_calibrated.ascii" : astronomical spectrum in wavenumbers (cm^-1) "fit20230811.log" PGOPHER fit log for global fit of v = 0, v2/v4 dyad, and v3 "PGOPHERfiles/CH3+_simulation_esi.pgo" PGOPHER simulation file for CH3+ "PGOPHERfiles/attrib_nu2nu4_MIRIcal.obs" PGOPHER line list for v2/v4 dyad "PGOPHERfiles/attrib_nu3_1994.obs" PGOPHER line list for v3 "PGOPHERfiles/master.obs" PGOPHER master line list

10.5281/zenodo.8436407

Cite

Citations (0)

Anomalous Intensities in the Infrared Emission of CH⁺ Explained by Quantum Nuclear Motion and Electric Dipole Calculations

The Astrophysical Journal (2021)

P. Bryan Changala David A. Neufeld B. Godard

Abstract The unusual infrared emission patterns of CH + , recently detected in the planetary nebula NGC 7027, are examined theoretically with high-accuracy rovibrational wavefunctions and ab initio dipole moment curves. The calculated transition dipole moments quantitatively reproduce the observed J -dependent intensity variation, which is ascribed to underlying centrifugal distortion-induced interference effects. We discuss the implications of this anomalous behavior for astrochemical modeling of CH + production and excitation, and provide a simple expression to estimate the magnitude of this effect for other light diatomic molecules with small dipole derivatives.

Diatomic molecule

10.3847/1538-4357/ac05c8

Cite

Citations (7)

SPECTROSCOPIC CHARACTERIZATION OF THE ELUSIVE GAUCHE-ISOPRENE BY HIGH RESOLUTION MICROWAVE SPECTROSCOPY

Proceedings of the 73rd International Symposium on Molecular Spectroscopy (2018)

J. Westerfield Michael McCarthy Steven T. Shipman Joshua H. Baraban Thanh Lâm Nguyễn

Isoprene

Characterization

10.15278/isms.2018.tk05

Cite

Citations (0)

Calcium Chemistry in Carbon-rich Circumstellar Environments: The Laboratory and Astronomical Discovery of Calcium Dicarbide, CaC₂ *

The Astrophysical Journal Letters (2024)

H. M. Sen Gupta P. Bryan Changala J. Cernicharo J. R. Pardo M. Agúndez

Abstract Calcium dicarbide, CaC 2 , has been characterized at high resolution in the laboratory, and its main isotopologue, 40 CaC 2 , has been assigned to 14 rotational emission lines between 14 and 115 GHz, including 12 previously unassigned lines, in the expanding molecular envelope of the evolved carbon star IRC+10216. Aided by high-level quantum calculations and measurements of multiple isotopologues, CaC 2 is determined to be a T-shaped molecule with a highly ionic bond linking the metal atom to the C 2 unit, very similar in structure to isovalent magnesium dicarbide (MgC 2 ). The excitation of CaC 2 is characterized by a very low rotational temperature of 5.8 ± 0.6 K and a kinetic temperature of 36 ± 16 K, similar to values derived for MgC 2 . On the assumption that the emission originates from a 30″ shell in IRC+10216, the column density of CaC 2 is (5.6 ± 1.7) × 10 11 cm −2 . CaC 2 is only the second Ca-bearing molecule besides CaNC and only the second metal dicarbide besides MgC 2 identified in space. Owing to the similarity between the predicted ion–molecule chemistry of Ca and Mg, a comparison of the CaC 2 abundance with that of MgC 2 and related species permits empirical inferences about the radiative association–dissociative recombination processes postulated to yield metal-bearing molecules in IRC+10216 and similar objects.

Carbon fibers

10.3847/2041-8213/ad3336

Cite

Citations (2)

Direct measurements of DOCO isomers in the kinetics of OD+CO

arXiv (Cornell University) (2017)

Thinh Bui Bryce Bjork P. Bryan Changala Thanh Lâm Nguyễn John F. Stanton

Quantitative and mechanistically-detailed kinetics of the reaction of hydroxyl radical (OH) with carbon monoxide (CO) have been a longstanding goal of contemporary chemical kinetics. This fundamental prototype reaction plays an important role in atmospheric and combustion chemistry, motivating studies for accurate determination of the reaction rate coefficient and its pressure and temperature dependence at thermal reaction conditions. This intricate dependence can be traced directly to details of the underlying dynamics (formation, isomerization, and dissociation) involving the reactive intermediates cis- and trans-HOCO, which can only be observed transiently. Using time-resolved frequency comb spectroscopy, comprehensive mechanistic elucidation of the kinetics of the isotopic analogue deuteroxyl radical (OD) with CO has been realized. By monitoring the concentrations of reactants, intermediates, and products in real-time, the branching and isomerization kinetics and absolute yields of all species in the OD+CO reaction are quantified as a function of pressure and collision partner.

Branching (polymer chemistry)

Reactive intermediate

10.48550/arxiv.1706.04689

Cite

Citations (1)

Identification of New {CIS} Vibrational Levels in the S 1 State of C 2 H 2

67th International Symposium on Molecular Spectroscopy (2012)

Joshua H. Baraban P. Bryan Changala Rachel G. Shaver Robert W. Field John F. Stanton

Identification

Source

Cite

Citations (0)

Photodissociation transition states characterized by chirped pulse millimeter wave spectroscopy

Proceedings of the National Academy of Sciences (2019)

Kirill Prozument Joshua H. Baraban P. Bryan Changala G. Barratt Park Rachel G. Shaver

Significance Transition states control results of molecular reactions. However, it is difficult to extract details about the transition state solely from the chemical products born from the transition state. This inability to experimentally characterize transition state limits our ability to predict and steer the outcomes of chemical processes. Here we describe the use of a recently developed, simultaneously broadband and high-resolution technique, chirped-pulse millimeter-wave spectroscopy, to measure the nascent product state distribution that results from the photolysis of vinyl cyanide and, from it, to infer properties of the transition state(s) involved. Insights gleaned from studies such as these are crucial to a detailed understanding of molecular quantum dynamics at a level that promises to allow us to calculate and manipulate chemistry.

Extremely high frequency

Transition state

10.1073/pnas.1911326116

Cite

Citations (15)