The Ionization and Disassociation of Molecules

The Ionization and Disassociation of Molecules Itzik Ben-Itzhak, Kevin Carnes, Jarlath McKenna, Max Sayler, Bishwanath Gaire, Nora Johnson, Siddique Khan, and Eli Parke By Nick Timme and Sam Fahrenholtz Funding Provided by the NSF August 2nd, 2007

Three Projects • Isotopic Water: Analyze data of proton collisions with isotopic water molecules • VERBOTEN! • VERBOTEN!

VERBOTEN!

Motivation – Isotopic Water (H2O, D2O, HDO) • Medical Physics • Isotopic Effects in the Ionization and Dissociation in Water • Bond Rearrangement

Experimental Setup

Coupling – HD Example • We only detect positively charge fragments • Possible Reactions • HD → HD+: Detect HD+ • HD → H + D+: Detect D+ • HD → H+ + D: Detect H+ • HD → H+ + D+: Detect H+ and D+

Coupling – HD Example • Coupled HD+ Equations (ε: Detector Efficiency, τ: Likelihood of a Random Coincidence) • M[HD+] = εN[HD+] • M[H+] = εN[H+ + D] + N[H+ + D+]ε(1-ε) • M[D+] = εN[H + D+] + N[H+ + D+]ε(1-ε) • M[H+ + D+] = ε2N[H+ + D+] + τN[H+ + D]N[H + D+] • 1st Iteration assume τ=0

Scaling Out Contaminations • -Air: Channel 32 • H2O-D2O: Channel 20 • H2O-HDO: Channel 19 • D2O-H2O: Channel 1,17 • D2O-HDO: Channel 19 • HDO-H2O: Channel 1,17 • HDO-D2O: Channel 20

Data Analysis Plan and Its Failure • Max’s decoupling program fails with 1 MeV data and succeeds with 4 MeV data • Use Itzik’s decoupling program on 4 MeV data, compare to the results of Max’s decoupling program • If they agree, use Itzik’s program to decouple 1 MeV data • Unfortunately, Itzik’s program failed to decouple the 4 MeV HDO data, but it did decouple 4 MeV H2O and D2O data

Two Alternative Methods • Skip Decoupling all together, only scale out contaminates, compare results • Combine decoupled H2O and D2O from Itzik’s program with coupled contamination free HDO in a new iterative scaling method

Iterative Contamination Removal • Accounts for Isotopic Oxygen in Scaling Channels • Obtains More Accurate Values Due to Iterative Method ith iteration in removing HDO from H2O, α is the isotopic ratio 017/O

4 MeV Method Comparison - HDO

4 MeV Method Comparison – H2O

4 MeV Method Comparison – D2O

Branching Ratios • Channel/Parent Channel • Example: H+/H2O+

Branching Ratio – HDO

Bond Rearrangement – HDO

Bond Rearrangement

Future Work • Develop a better decoupling method

Conclusion • We analyzed our isotopic water data and found isotopic dependence on branching ratios and bond rearrangement. • VERBOTEN! • VERBOTEN!

Acknowledgments • Itzik’s group: Itzik, Kevin, Jarlath, Max, Bishwanath, Nora, Siddique, and Eli • The REU Program • Larry Weaver • Kristan Corwin • Ethicists Bruce and Amy

The Ionization and Disassociation of Molecules