Modelling Metal Foam Formation in Helium Nanodroplets David McDonagh, The Centre for Interdisciplinary Science Project Supervisor: Professor Andrew Ellis,

Slides:



Advertisements
Similar presentations
Infrared spectroscopy of metal ion-water complexes
Advertisements

Quantum Mechanics Calculations II Apr 2010 Postgrad course on Comp Chem Noel M. O’Boyle.
Spectra, Structures, and Dynamics of Weakly Bound Clusters from Dimers to Nonamers Wolfgang Jäger Department of Chemistry, University of Alberta.
Silver Nyambo Department of Chemistry, Marquette University, Wisconsin Resonance enhanced two-photon ionization (R2PI) spectroscopy of halo-aromatic clusters.
NABIL F. FARUK, HUI LI, JING YANG, ROBERT J. LE ROY & PIERRE-NICHOLAS ROY Simulation Studies of the Vibrational Dynamics of para- Hydrogen Clusters 1.
The iron content of runoff from a banana ranch is a necessary analytical parameter to analyze. A 25.0mL sample of the runoff was acidified with HNO3 and.
Ivan Janeček, Daniel Hrivňák, and René Kalus Department of Physics, University of Ostrava, Ostrava, Czech Republic Supported by the Grant Agency of the.
Chapter 14 Applications of Ultraviolet-Visible Molecular Absorption Spectrometry.
DFT STUDY OF SOLVENT EFFECTS ON CONFORMATIONAL EQUILIBRIA AND
1 A Density Functional Study of the Competing Processes Occuring in Solution during Ethylene Polymerisation by the Catalyst (1,2Me 2 Cp) 2 ZrMe + Kumar.
Modelling Water Dimer Band Intensities and Spectra Matt Barber Jonathan Tennyson University College London 29 th September 2010
Ab initio REMPI Erlendur Jónsson. MSc project Electronically excited states of HX(H 2 O) n After some trial calculations, this morphed into just calculations.
Simulation of X-ray Absorption Near Edge Spectroscopy (XANES) of Molecules Luke Campbell Shaul Mukamel Daniel Healion Rajan Pandey.
Outline Final Comments on Titrations/Equilibria Titration of Base with a strong acid End-point detection Choice of indicators Titration Curve method Start.
Orbital-Dependent Density Functionals for Catalysis Pd interactions with polyenes in complexes Boris B. Averkiev, Yan Zhao, and Donald G. Truhlar, University.
AS Chemistry Unit 1 Module 3 –The Periodic Table
Time out—states and transitions Spectroscopy—transitions between energy states of a molecule excited by absorption or emission of a photon h =  E = E.
Infrared spectroscopy of Li(methylamine) n (NH 3 ) m clusters Nitika Bhalla, Luigi Varriale, Nicola Tonge and Andrew Ellis Department of Chemistry University.
TOF Mass Spectrometer &
CHEMISTRY 2000 Topic #1: Bonding – What Holds Atoms Together? Spring 2010 Dr. Susan Lait.
Institute of Experimental Physics 1 Wolfgang E. Ernst Xe and Rb Atoms on Helium Nanodroplets: is the van der Waals Attraction Strong Enough to Form a Molecule?
Aloke Das Indian Institute of Science Education and Research, Pune Mimicking trimeric interactions in the aromatic side chains of the proteins: A gas phase.
Theoretical Study of Photodissociation dynamics of Hydroxylbenzoic Acid Yi-Lun Sun and Wei-Ping Hu* Department of Chemistry and Biochemistry, National.
Electronic spectra of Polyaromatic hydrocarbons in helium
Hot molecules in helium nanodroplets: a new route to optical spectra Benjamin Shepperson, Adrian Boatwright, Cheng Feng, Daniel Spence, Shengfu.
1.Solvation Models and 2. Combined QM / MM Methods See review article on Solvation by Cramer and Truhlar: Chem. Rev. 99, (1999)
Electronic spectroscopy of Li(NH 3 ) 4 Nitika Bhalla, Luigi Varriale, Nicola Tonge and Andrew Ellis Department of Chemistry University of Leicester UK.
Infrared Photodissociation Spectroscopy of Silicon Carbonyl Cations
The Electronic Spectra of Coordination Compounds.
Arrangement of Electrons. Spectroscopy and the Bohr atom (1913) Spectroscopy, the study of the light emitted or absorbed by substances, has made a significant.
States and transitions
The iron content of runoff from a banana ranch is a necessary analytical parameter to analyze. A 25.0mL sample of the runoff was acidified with HNO3 and.
Pulsed-jet discharge matrix isolation and computational study of Bromine atom complexes: Br---BrXCH 2 (X=H,Cl,Br) OSU 66 th International Symposium on.
Using computer modelling to help design materials for optical applications Robert A Jackson Chemical & Forensic Sciences School of Physical & Geographical.
I. Computational Studies of the Cone and 1,2,3 Alt Calix[6]arene Bis-Crown-4 Isomers Meghan N. Lawson, Michael T. Blanda, Sara J. Staggs, Lauren N. Sederholm,
Bonding & dynamics of CN-Rg and C 2 -Rg complexes Jiande Han, Udo Schnupf, Dana Philen Millard Alexander (U of Md)
Sequential Oxidation of Group 6 Transition Metal Suboxide Clusters Caroline Chick Jarrold Department of Chemistry, Indiana University November 30, 2015.
A Method to Rapidly Predict the Injection Rate in Dye Sensitized Solar Cells. Daniel R. Jones and Alessandro Troisi Department of Chemistry and Centre.
Rotationally-Resolved Spectroscopy of the Bending Modes of Deuterated Water Dimer JACOB T. STEWART AND BENJAMIN J. MCCALL DEPARTMENT OF CHEMISTRY, UNIVERSITY.
Mike Lindsay * and Roger Miller University of North Carolina at Chapel Hill OSU International Symposium on Molecular Spectroscopy, TI02, 6/22/2006 * Current.
TURBOMOLE Lee woong jae.
M. KUMRU, M. KOCADEMİR, H. M. ALFANDA Fatih University, Faculty of Arts and Sciences, Physics Department, Büyükçekmece, Istanbul.
Infrared Photodissociation Spectroscopy of TM + (N 2 ) n (TM=V,Nb) Clusters E. D. Pillai, T. D. Jaeger, M. A. Duncan Department of Chemistry, University.
LITERATURE SEARCH ASSIGNMENT A) Properties of diatomic molecules A diatomic molecule is a molecule composed of two atoms. For homonuclear diatomics the.
Ab Initio and Experimental Studies of the E Internal Rotor State of He-CH 3 F Kelly J. Higgins, Zhenhong Yu, and William Klemperer, Department of Chemistry.
High Resolution Microwave Spectra of He N – and (H 2 ) N – Linear Molecule Clusters Wolfgang Jäger Department of Chemistry, University of Alberta, Edmonton,
Quantum Methods For Adsorption
Infrared Resonance Enhanced Photodissociation (IR- REPD) Spectroscopy used to determine solvation and structure of Ni + (C 6 H 6 ) n and Ni + (C 6 H 6.
INTRODUCTION TO SPECTROSCOPY
Infrared Resonance Enhanced Photodissociation of Au + (CO) n Complexes in the Gas Phase Joe Velasquez, III, E. Dinesh Pillai and Michael A. Duncan Department.
Hydrogen-bond between the oppositely charged hydrogen atoms It was suggested by crystal structure analysis. A small number of spectroscopic studies have.
Tao Peng and Robert J. Le Roy
Itaru KURUSU, Reona YAGI, Yasutoshi KASAHARA, Haruki ISHIKAWA Department of Chemistry, School of Science, Kitasato University ULTRAVIOLET AND INFRARED.
IR photodepletion and REMPI spectroscopy of Li(NH 2 Me) n clusters Tom Salter, Victor Mikhailov, Corey Evans and Andrew Ellis Department of Chemistry International.
Calculation of Excitations of Superfluid Helium Nanodroplets Roman Schmied and Kevin K. Lehmann Department of Chemistry Princeton University 60 th Ohio.
Microwave Spectroscopy and Internal Dynamics of the Ne-NO 2 Van der Waals Complex Brian J. Howard, George Economides and Lee Dyer Department of Chemistry,
Laser spectroscopy of a halocarbocation: CH 2 I + Chong Tao, Calvin Mukarakate, and Scott A. Reid Department of Chemistry, Marquette University 61 st International.
The Rotational Spectrum of the Water–Hydroperoxy Radical (H 2 O–HO 2 ) Complex Kohsuke Suma, Yoshihiro Sumiyoshi, and Yasuki Endo Department of Basic Science,
Using a tight-binding approximation to compute the electronic structure of sensitizer molecules adsorbed onto TiO 2 surfaces. Daniel R. Jones & Alessandro.
A New Potential Energy Surface for N 2 O-He, and PIMC Simulations Probing Infrared Spectra and Superfluidity How precise need the PES and simulations be?
Spectroscopy of (He) N -Molecule Clusters: Tracing the Onset of Superfluidity Yunjie Xu and Wolfgang Jäger Department of Chemistry, University of Alberta,
Statistical Mechanics and Multi-Scale Simulation Methods ChBE
Atoms and Atomic Theory
International Symposium on Molecular Spectroscopy
Analytical methods Prepared By Dr. Biswajit Saha.
F H F O Semiexperimental structure of the non rigid BF2OH molecule (difluoroboric acid) by combining high resolution infrared spectroscopy and ab initio.
Stepwise Internal Energy Control for Protonated Methanol Clusters
Absence of Ion-Binding Affinity in the Putatively Inactivated Low-[K+] Structure of the KcsA Potassium Channel  Céline Boiteux, Simon Bernèche  Structure 
Kristen E. Norman, Hugh Nymeyer  Biophysical Journal 
Presentation transcript:

Modelling Metal Foam Formation in Helium Nanodroplets David McDonagh, The Centre for Interdisciplinary Science Project Supervisor: Professor Andrew Ellis, Department of Chemistry ABSTRACT: Conflicting experimental evidence for metal foam formation in aluminium-doped helium nanodroplets highlights the need for a deeper understanding of the favourable conditions for metastable complexes to form. Potential energy surface calculations of dimers were superimposed to simulate the environment of both magnesium and aluminium-doped nanodroplets. UV-Vis calculations were then carried out at predicted local minima and compared to experimental values. In the magnesium system, UV-Vis calculations indicate a preferred metastable state partially stabilised by favourable helium-helium interactions. The same methods applied to the aluminium system found no local minima, and UV-Vis calculations at the suspected distance of one bubble diameter produced a red-shift significantly beyond that found by experiment. These results indicate metastable complexes are unlikely to form in aluminium-doped droplets, and double-peaked UV-Vis spectra for this system is likely a result of a distortion of the bubble cavity. A helium density profile of an embedded magnesium dimer, Przystawik et al References: [1] Toennies, J.P., & Vilesov, A. F. (2004). Angewandte Chemie, 43 (20), [2] Ancilotto, F., & Barone, V. (1997). Chemical Physics Letters, 274 (1-3), [3] Przystawik, A. et al. (2008). Physical Review A, 78(2) [4] Hernando, A. et al. (2008). Physical Review B, 78(18) [5] Krasnokutski, S. A., & Huisken, F. (2011). Journal of Physical Chemistry A, 115 [6] Spence, D. et al. (2014). International Journal of Mass Spectrometry, 365 Introduction A growing body of research now involves the study of molecular complexes in helium nanodroplets, most notably due to the free rotation and translation of molecules not available in other cooling techniques, and the solvent providing a medium transparent to ultraviolet and infrared radiation [1]. The degree of solvation has been found to differ depending on the molecule used, where the level of interaction between helium atoms can result in a surface or solvated state, in the latter case resulting in clustering of the dopant species [2]. In magnesium-doped nanodroplets, however, an interesting case is observed. Resonant-two- ionisation (R2PI) spectra indicate magnesium atoms enter a solvated state, but remain delocalised at a preferred distance, producing a metastable complex or ‘foam’ [3]. Further evidence for this is found in potential energy surface and helium density calculations, indicating helium atoms between dopants provide several potential energy barriers, preventing cluster formation [4]. From a lack of Al n + clusters in mass spectrometric analyses of aluminium-doped droplets, and a comparable UV-Vis spectrum to the magnesium system, it has been suggested that the same behaviour may be true for aluminium [5]. However, more recent experimental work appears to contradict these findings [6]. Methods To assess the differences in these two systems, a more detailed analysis of the potential energy surface of magnesium-doped nanodroplets was carried out, and UV-Vis calculations were run to assess the likelihood of each metastable state from experimental values. This was then repeated for aluminium-doped nanodroplets. Mg 2, MgHe and He 2 potential energy surfaces were calculated at the Coupled Cluster level of theory up to double excitations, with triple excitations treated using perturbation theory (CCSD(T)). The augmented correlation consistent polarised valence quadrupole zeta basis set (aug-cc-pVQZ) was used in each case, with the addition of bond functions developed by F. Tao & Pan (1992) for weakly bound systems found to be more consistent with literature values for MgHe. Superimposing dimer potentials was done assuming a spherical bubble cavity, shown in figure 1. UV-Vis spectra for the 3  3p transition were calculated at the Configuration Interaction level of theory up to double excitations, with results shown in table 1. To accurately model the aluminium open-shelled systems, Density Functional Theory (DFT) was used, where the three parameter hybrid functional developed by Becke (1993) with the G* Pople basis set was found to be most consistent with literature values. In light of this, UV-Vis spectra were calculated using the same functional and basis set, using Time-Dependent Density Functional Theory (TD-DFT). All calculations were carried out in the Gaussian 03 Software Package, with orbitals rendered in Chemdraw. Discussion The potential energy curves calculated for magnesium-doped droplets are in good agreement with literature values [3], and several local minima are observed. Through extending this to three dopant atoms, the 10.2 Å minimum was found to be the most favourable metastable state. Calculated UV-Vis spectra for this system appear to confirm this, where transitions with dopants placed at a distance of 10.2 Å show a red shift most consistent with experimental values [3]. Interestingly, in using a solvation shell density calculated from previous work [4], solvent atoms in neighbouring shells are placed at the helium-helium equilibrium distance when dopants are placed at 10.2 Å. This could therefore act in further stabilising this metastable state. The most accurate dimer potentials for aluminium-doped nanodroplets show no evidence of local minima, and calculated UV-Vis values show a redshift significantly beyond that observed experimentally. This work hence finds evidence in agreement with recent mass spectrometric analysis that aluminium atoms cluster in helium nanodroplets [6]. A more detailed analysis of the spectra of aluminium-doped nanodroplets with single dopant atoms is recommended to assess whether the double- peaked spectrum for this system is due to delocalisation at distances greater than the bubble diameter, or a distortion of the bubble cavity. Figure 1: The embedded potential energy curve predicted for two magnesium atoms solvated in a helium nanodroplet. Local minima are observed at 10.2 Å and 13.7 Å, with binding energies of approximately 9 cm -1 and 5 cm -1, respectively. Table 1: UV-Vis spectra for the 3p  3s transition. The experimental gas phase value is taken from NIST (2014), and the embedded magnesium data is taken from Przystawik et al. (2008). The embedded environment was simulated using a number explicit solvent molecules based on helium density calculations for this system [4]. Mg gas phase (nm) Embedded Mg (nm) Two embedded Mg atoms at 10.2 Å (nm) Two embedded Mg atoms at 13.7 Å (nm) Experimental CIS(D)