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Personal profile

Research interests

Dynamics of Reactive and Inelastic Molecular Collisions

Collisions abound in almost all chemical processes of practical interest, resulting either in chemical reactions or energy transfer. We aim to understand what happens during intermolecular collisions by preparing systems as precisely as possible and then examining the detailed motions of the products immediately afterwards, mainly through novel types of laser spectroscopy. This work is carried out jointly with Dr Matt Costen (see our joint research group webpages).

1. Dynamics of Collisions at Liquid Surfaces

Despite their widespread practical importance in, e.g., heterogeneous atmospheric chemistry and the combustion of liquid fuels, collisions at the gas-liquid interface remain relatively unexplored fundamentally. We have developed a successful, laser-based method to study reactive and inelastic collisions of gas-phase radicals at liquid surfaces (Figure 1). We have also demonstrated that it can be exploited as a new type of analytical probe of complex surfaces such as those of ionic liquids.


Figure 1. Schematic reaction of gas-phase O(3P) atoms at the surface of the long-chain hydrocarbon, squalane (C30H62).

2. Dynamics of Inelastic Collisions of Open-Shell Radicals

Small open-shell radicals, such as OH, CN and NO, are the key species in many gas-phase environments. Their intermolecular collisions govern the dissipation of energy and are also crucial in the interpretation of spectroscopic probes of concentrations and temperatures. We have developed several methods, including polarisation spectroscopy and frequency-modulated absorption spectroscopy, to study such collisions, with particular focus on the destruction of rotational polarisation (Figure 2).


Figure 2. 2-colour polarisation spectroscopy measurements of the decay of orientation of OH(X)v = 0 in different rotational levels in collisions with Ar and He at low (300 mTorr, blue) and high (1000 mTorr, red) pressures.

3. Dynamics of High-Energy Reactive Collisions

In collaboration with Prof Tim Minton at Montana State University, we have been involved in a number of studies of the dynamics of collisions of O(3P) atoms generated from a unique high-energy source. This has been exploited to study reactions at selected liquid surfaces (see above), complemented by realistic molecular dynamics simulations (Figure 3), and in on-going work on benchmark elementary gas-phase reactions such as O(3P) + D2.


Figure 3. Snapshot molecular dynamics simulations of the surfaces of the ionic liquids C2mim NTf2 (upper) and C12mim NTf2 (lower), showing the preferential accumulation of the longer alkyl chains at the surface of the liquid.

Research Group Contact Details

Roles & Responsibilities

  • Head of Dynamics and Structure research grouping
  • Member of Institute of Chemical Sciences Management Group
  • MChem Study Director
  • School of Engineering & Physical Sciences Representative of Heriot-Watt University Senate

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Research Output

  • Probing Conformational Heterogeneity at the Ionic Liquid–Vacuum Interface by Reactive-Atom Scattering

    Smoll, E. J., Purcell, S. M., D’Andrea, L., Slattery, J. M., Bruce, D. W., Costen, M. L., McKendrick, K. G. & Minton, T. K., 17 Jan 2019, In : Journal of Physical Chemistry Letters. 10, 2, p. 156-163 8 p.

    Research output: Contribution to journalArticle

    Open Access
  • 5 Citations (Scopus)
    6 Downloads (Pure)

    Real-space laser-induced fluorescence imaging applied to gas-liquid interfacial scattering

    Bianchini, R. H., Roman, M. J., Costen, M. L. & McKendrick, K. G., 7 Aug 2019, In : The Journal of Chemical Physics. 151, 5, 12 p., 054201.

    Research output: Contribution to journalArticle

    Open Access
  • 2 Citations (Scopus)
    9 Downloads (Pure)

    Collision-Energy Dependence of the Uptake of Hydroxyl Radicals at Atmospherically Relevant Liquid Surfaces

    Bianchini, R., Tesa-Serrate, M. A., Costen, M. L. & McKendrick, K. G., 29 Mar 2018, In : Journal of Physical Chemistry C. 122, 12, p. 6648-6660 13 p.

    Research output: Contribution to journalArticle

    Open Access
  • 3 Citations (Scopus)
    29 Downloads (Pure)

    Determining the Composition of the Vacuum-Liquid Interface in Ionic-Liquid Mixtures

    Smoll, E. J., Tesa-Serrate, M. A., Purcell, S., D'Andrea, L., Bruce, D. W., Slattery, J. M., Costen, M. L., Minton, T. K. & McKendrick, K. G., 1 Jan 2018, In : Faraday Discussions. 206, p. 497-522 26 p.

    Research output: Contribution to journalArticle

    Open Access
  • 11 Citations (Scopus)
    26 Downloads (Pure)


    Rotationally Inelastic Scattering of NO(A2Sigma+)+Ar: Differential cross sections and rotational angular momentum polarization

    Costen, M. L. (Creator), McKendrick, K. G. (Contributor), Townsend, D. (Contributor), Sharples, T. R. (Contributor) & Luxford, T. F. M. (Contributor), Heriot-Watt University, 15 Sep 2015


    Comparative stereodynamics in molecule-atom and molecule-molecule rotational energy transfer: NO(A2Σ+) + He and D2.

    Costen, M. L. (Creator), McKendrick, K. G. (Creator), Townsend, D. (Creator), Luxford, T. F. M. (Creator) & Sharples, T. R. (Creator), Heriot-Watt University, 29 Jul 2016


    Experimental testing of ab initio potential energy surfaces: Stereodynamics of NO(A2Σ+) + Ne inelastic scattering at multiple collision energies

    Costen, M. L. (Creator), Sharples, T. R. (Creator), McKendrick, K. G. (Creator) & Luxford, T. F. M. (Creator), Heriot-Watt University, 31 Oct 2016


    Pair-correlated stereodynamics for diatom-diatom rotational energy transfer: NO(A2Σ+) + N2

    Luxford, T. F. M. (Creator), Sharples, T. R. (Creator), McKendrick, K. G. (Creator) & Costen, M. L. (Creator), Heriot-Watt University, 21 Mar 2017



    Fellow of the Royal Society of Edinburgh

    McKendrick, Kenneth George (Recipient), 2011

    Prize: Election to learned society

    Royal Society / Leverhulme Trust Senior Research Fellowship

    McKendrick, Kenneth George (Recipient), 2008

    Prize: Fellowship awarded competitively

    RSC Chemical Dynamics Award 2015

    McKendrick, Kenneth George (Recipient), 3 May 2015

    Prize: Prize (including medals and awards)


    Reaction dynamics is really interesting, but is it useful?

    Kenneth George McKendrick (Speaker)

    25 Aug 2019

    Activity: Talk or presentationInvited talk

    International Symposium on Molecular Beams

    Kenneth George McKendrick (Chair)

    23 Jun 201928 Jun 2019

    Activity: Participating in or organising an eventParticipation in conference

    Annual Review of Physical Chemistry (Journal)

    Kenneth George McKendrick (Guest editor)

    1 Jul 20191 Apr 2021

    Activity: Publication peer-review and editorial workEditorial activity

    Real-Space Imaging of Molecules Scattered from Liquid Surfaces

    Kenneth George McKendrick (Speaker)

    10 Jul 2019

    Activity: Talk or presentationInvited talk

    Real-Space Imaging of OH Radicals Scattering from Liquid Surfaces

    Kenneth George McKendrick (Speaker)

    10 Jul 2018

    Activity: Talk or presentationInvited talk