Rocket Propulsion Systems

An understanding of the energetics and dynamics of elementary reactions of boron monoxide (BO) radicals with key unsaturated hydrocarbons [acetylene, ethylene, methylacetylene allene), diacetylene, and benzene] and the inherent formation of small boron-bearing molecules is of considerable interest to understand boron combustion processes, to the physical organic commu-nity due to the isoelectronic nature of boron monoxide and the cyano radical, and to the reaction dynamics community (reaction dynamics of transient radicals) both from the experimental and theoretical viewpoints. Computations are conducted in collaboration with Profs. Bartlett (University of Florida), Mebel (FIU), and Chang (NDHU, Taiwan). Boron monoxide presents a crucial transient radical in boron-based combustion processes, but the reaction dynamics of this radical have not been investigated so far. Here, due to its high energy density, boron has long been regarded as a good candidate for rocket fuel additives. This interest has also been expanded recently to ramjet and scramjet propulsion systems. The oxidation of boron is initially unable to reach full energy release due to the formation of boron oxide (B₂O₃) as an inert layer, which coats the non-reacted boron preventing further reaction. Essentially, the carbon-based fuel ignites and reaches a high enough temperature to remove the boron oxide layer, which, in turn, allows clean boron to be accessible for the combustion phase. The very first boron-bearing species formed in these processes is the boron oxide radical (BO), which can either react to boron oxide (B₂O₃) or with the hydrocarbon fuel to form carbon-, hydrogen-, oxygen-, and boron-bearing molecules (CHOB molecules). Compared to ‘classical’ hydrocarbon flames, the incorporation of boron results in a more complex, high temperature (1,800 – 4,000 K) organo boron chemistry. These considerations have led to the development of boron-based combustion models involving detailed experimental input parameters such as reaction products, intermediates, and rate constants. Although the reaction dynamics of boron atoms with hydrocarbon molecules have emerged during the recent years utilizing the crossed molecular beam approach thus accessing the B/C/H system, dynamics studies in the B/O/C/H system, in particular those involving reactions of the boron monoxide radical (BO) with hydrocarbon molecules, have been elusive to date. Therefore, a critical shortcoming of all boron-based combustion models is the fact that elementary reactions in the B/O system have never been coupled with those occurring in the B/C/H system. Crossed beam studies of the reaction of boron monoxide (BO) with acetylene (C₂H₂) showed that the HCCBO molecule plus atomic hydrogen can be formed.

Recent Selected Publications

1. N. Balucani, O. Asvany, Y. T. Lee, R. I. Kaiser, N. Galland, Y. Hannachi, Observation of borirene from crossed beam reaction of boron atoms with ethylene, J. Am. Chem. Soc. 122 11234-11235 (2000). (PDF)

2. N. Balucani, O. Asvany, Y.T. Lee, R.I. Kaiser, N. Galland, M.T. Rayez, Y. Hannachi, Gas-phase detection of the HBCC(X¹Σ) molecule: A combined crossed beam and computational study of the B(²P) + C₂H₂(¹Σ_g⁺) reaction, J. Comp. Chem. (special issue in honor of Prof. Schleyers 70^th birthday), 22, 1359-1365 (2001). (PDF)

3. R.I. Kaiser, H.F. Bettinger, Gas-Phase Detection of the elusive Benzoborirene Molecule, Angew. Chem. Int. Ed., 41, 2350-2352 (2002). (PDF)

4. D. Sillars, R.I. Kaiser, N. Galland, Y. Hannachi, Crossed-beam reaction of boron atoms, B(²P_j), with dimethylacetylene, CH₃CCCH₃(X¹A_1g): Untangling the reaction dynamics to form the 1,2-dimethylene-3-bora-cyclopropane molecule, J. Phys. Chem. A, 107, 5149-5156 (2003). (PDF)

5. R.I. Kaiser, N. Balucani, N. Galland, F. Caralp, M.T. Rayez, Y. Hannachi, Unraveling the chemical dynamics of bimolecular reactions of ground state boron atoms, B(²P_j), with acetylene, C₂H₂(X¹Σ_g⁺). Phys. Chem. Chem. Phys., 6, 2205-2210 (2004). (PDF)

6. H.F. Bettinger, R.I. Kaiser, Reaction of benzene and boron atom: Mechanism of Formation of Benzoborirene and Hydrogen Atom, JPCA, 108, 4576-4586 (2004). (PDF)

7. F. Zhang, Y. Guo, X. Gu, R.I. Kaiser, A Crossed Molecular Beam Study on the Reaction of Boron Atoms, B(²P_j), with Benzene, C₆H₆(X¹A_1g), and D6-bezene C₆D₆(X¹A_1g), CPL 440, 56-63 (2007). (PDF)

8. J.G. Longenecker, A.M. Mebel, R.I. Kaiser, First Infrared Spectroscopic Detection of the Monobridged (B₂H₅; C_2v) Diboranyl Radical in Low Temperature Diborane Ices, Inorganic Chemistry 46, 5739-2743 (2007). (PDF)

9. F. Zhang, A.H.H. Chang, X. Gu, R.I. Kaiser, A Crossed Molecular Beam Study on the Reaction of Boron Atoms, B(²P_j), with Allene, H₂CCCH₂(X¹A₁), JPCA 111, 13305-13310 (2007). (PDF)

10. F. Zhang, X. Gu, R.I. Kaiser, H.F. Bettinger, A Reinvestigation of the Gas Phase Reaction of Boron Atoms, ¹¹B(²P_j)/¹⁰B(²P_j) with Acetylene, C₂H₂(X¹Σ_g⁺), Chem. Phys. Lett. 450 178-185 (2008). (PDF)

11. F. Zhang, C.H. Kao, A.H.H. Chang, X. Gu, Y. Guo, R.I Kaiser, A Crossed Molecular Beam Study on the Reaction of Boron Atoms with Methylacetylene and Partially Deuterated Methylacetylene, Chem. Phys. Chem. 9, 95-105 (2008). (PDF)

12. F. Zhang, X. Gu, R.I. Kaiser, N. Balucani, A.H.H. Chang, A Crossed Beam and Ab Initio Study of the Reaction of Atomic Boron with Ethylene, JPCA 112, 3837-3845 (2008). (PDF)

231. N. Balucani, F. Zhang, R.I. Kaiser, Elementary Reactions of Boron Atoms with Hydrocarbons - Toward the Formation of Organo-Boron Compounds, Chem. Rev. 110, 5107-5127 (2010). (PDF)

13. P. Maksyutenko, F. Zhang, Y.S. Kim, R.I. Kaiser, S.H. Chen, C.C. Wu, A.H.H. Chang, Untangling the Chemical Dynamics of the Reaction of Boron Atoms, ¹¹B(²P_j), with Diacetylene, C₄H₂(X¹Σ_g⁺) - A Crossed Molecular Beams and Ab Initio Study, JPCA 114, 10936-10943 (2010). (PDF)

14. C.P. Ennis, R.I. Kaiser, Mechanistical Studies on the Electron-Induced Degradation of Polymers: Polyethylene, Polytetrafluoroethylene, and Polystyrene, PCCP 12, 14884-14901 (2010). (PDF)

15. C.P. Ennis, R.I. Kaiser, Mechanistical Studies on the Electron-Induced Degradation of Polymers: polymethylmethacrylate and Kapton, PCCP 12, 14902-14915 (2010). (PDF)

16. F. Zhang, P. Maksyutenko, R.I. Kaiser, A.M. Mebel, A. Gregusova, S. Ajith Perera, R.J. Bartlett, Gas Phase Synthesis of the Imidoborane Molecule (HNBH) - An Isoelectronic Molecule of Acetylene (HCCH), JPCA 114, 12148-12154 (2010). (PDF)

17. D.S.N. Parker, F. Zhang, P. Maksyutenko, R.I. Kaiser, A.H.H. Chang, A Crossed Beam and ab initio Investigation of the Reaction of Boron Monoxide (¹¹BO; X²Σ⁺) with Acetylene (C₂H₂; X¹Σ_g⁺), PCCP 13, 8560-8570 (2011). (PDF)

18. P. Maksyutenko, D.S.N. Parker, F. Zhang, R.I. Kaiser, An LIF Characterization of Supersonic BO (X²Σ⁺) and CN (X²Σ⁺) Radical Sources for Crossed Beam Studies, RSI, 82, 083107/1-7 (2011). (PDF)

19. C. Ennis, H. Yuan, S.J. Sibener, R.I. Kaiser, On The Chemical Processing of Hydrocarbon Surfaces by Fast Oxygen Ions, PCCP, 13, 17870-17884 (2011). (PDF)

20. D.S.N. Parker, F. Zhang, P. Matsuyenko, R.I. Kaiser, S.H. Chen, A.H.H. Chang, A Crossed Beam and Ab Initio Investigation On The Formation of Vinyl Boron Monoxide (C₂H₃BO; X¹A') via Reaction of Boron Monoxide (¹¹BO; X²Σ⁺) with ethylene (C₂H₄; X¹A_g), Phys. Chem. Chem. Phys., 14, 11099-11106 (2012). (PDF)

21. S. Maity, R.I. Kaiser, Electron Irradiation of Carbon Disulfide - Oxygen Ices: Toward the Formation of Sulfur-Bearing Molecules in Interstellar Ices, Ap. J. 773, 184/1-184/8 (2013). (PDF)

22. D.S.N. Parker, N. Balucani, D. Stranges, R.I. Kaiser, A.M. Mebel, A Crossed Beam and ab Initio Investigation on the Formation of Boronyldiacetylene (HCCCC¹¹BO; X¹Σ⁺) via the Reaction of the Boron Monoxide Radical (¹¹BO; X²Σ⁺) with Diacetylene (C₄H₂; X¹Σ_g⁺), J. Phys. Chem. A., 117, 8189-8198 (2013). (PDF)

23. S. Maity, D.S.N. Parker, B.B. Dangi, R.I. Kaiser, S. Fau, A. Perera, R.J. Bartlett, A Crossed Molecular Beam and Ab-Initio Investigation of the Reaction of Boron Monoxide (BO; X²Σ⁺) with Methylacetylene (CH₃CCH; X¹A₁): Competing Atomic Hydrogen and Methyl Loss Pathways, J. Phys. Chem. A., 117, 11794-11807 (2013). (PDF)

24. D.S.N. Parker, B.B. Dangi, N. Balucani, D. Stranges, A.M. Mebel, R.I. Kaiser, Gas-Phase Synthesis of Phenyl Oxoborane (C₆H₅BO) via the Reaction of Boron Monoxide with Benzene, JOC, 78, 11896-11900 (2013). (PDF)

25. R.I. Kaiser, S. Maity, B.B. Dangi, Y.S. Su, B-J Sun, A.H.H. Chang, A crossed molecular beam and ab initio investigation of the exclusive methyl loss pathway in the gas phase reaction of boron monoxide (BO; X²Σ⁺) with dimethylacetylene (CH₃CCCH₃; X¹A_1g), Phys. Chem. Chem. Phys., 16, 989-997 (2014). (PDF)

26. D.S.N. Parker, R.I. Kaiser, A.M. Mebel, The role of isovalency in the reactions of the cyano (CN), boron monoxide (BO), silicon nitride (SiN), and ethynyl (C₂H) radicals with unsaturated hydrocarbons acetylene (C₂H₂) and ethylene (C₂H₄), Chem. Soc. Rev., 43, 2701-2713 (2014). (PDF)

27. S. Maity, D.S.N. Parker, R.I. Kaiser, B. Ganoe, S. Fau, A. Perera, R.J. Bartlett, Gas-Phase Synthesis of Boronylallene (H₂CCCH(BO)) under Single Collision Conditions: A Cross Molecular Beams and Computational Study, J. Phys. Chem. A, 118, 3810-3819 (2014). (PDF)

28. T. Yang, D.S.N. Parker, B.B. Dangi, R.I. Kaiser, D. Stranges, Y.H. Su, S.Y. Chen, A.H.H. Chang, A.M. Mebel, Directed Gas-Phase Formation of the Ethynylsulfidoboron Molecule, JACS., 136, 8387-8392 (2014). (PDF) (Supplemental Information) (Data Files)

29. T. Yang, B.B. Dangi, D.S.N. Parker, R.I. Kaiser, Y. An, A.H.H. Chang, A Combined Crossed Molecular Beams and ab initio Investigation on the Formation of Vinylsulfidoboron (C₂H₃¹¹B³²S), Phys. Chem. Chem. Phys., 16, 17580-17587 (2014). (PDF) (Supplemental Information)

30. S. Maity, B.B. Dangi, D.S.N. Parker, R.I. Kaiser , Y. An, B.J. Sun, A.H.H. Chang, Combined Crossed Molecular Beam and ab Initio Investigation of the Multichannel Reaction of Boron Monoxide (BO; X²Σ⁺) with Propylene (CH₃CHCH₂; X¹A'): Competing Atomic Hydrogen and Methyl Loss Pathways, J. Phys. Chem. A,118, 9632-9645 (2014). (PDF)

31. S. Maity, B.B. Dangi, D.S.N. Parker, R.I. Kaiser, H-M Lin, H-P E, B-J Sun, A.H.H. Chang, Combined Crossed Molecular Beam and ab Initio Investigation of the Reaction of Boron Monoxide (BO; X²Σ⁺) with 1,3-Butadiene (CH₂CHCHCH₂; X¹A_g) and its Deuterated Counterparts , J. Phys. Chem. A,119, 1094-1107 (2015). (PDF)

32. R.I. Kaiser, N. Balucani, Exploring the Gas Phase Synthesis of the Elusive Class of Boronyls and the Mechanism of Boronyl Radical Reactions under Single Collision Conditions, Accounts of Chemical Research. 50, 1154-1162 (2017). (PDF)