\documentclass[11pt]{article}

\usepackage{hrms}

%% *-----------------------------------------------------------------------------------------*

\title{VUV PHOTOIONIZATION SPECTROSCOPY OF INTERSTELLAR NITRILES}

\author{\FirstName H.R. \LastName HRODMARSSON, \underline{\FirstName M. \LastName SCHWELL}, \FirstName N. \LastName FRAY}
\address{Laboratoire Interuniversitaire des Syst\`emes Atmosph\'eriques, CNRS UMR 7583, Universit\'e Paris-Est Cr\'eteil et Universit\'e
Paris Cit\'e, IPSL, 61 av. G\'en\'eral de Gaulle, 94010 Cr\'eteil, France}

\author{\FirstName E.-L. \LastName ZINS}
\address{De la Mol\'ecule aux Nano-objets: R\'eactivit\'e, Interactions et Spectroscopies, CNRS UMR 8233, Sorbonne Universit\'e, 4 place Jussieu Tour 53, 75252 Paris cedex 05}

\author{\FirstName J.-C. \LastName GUILLEMIN}
\address{Institut des Sciences Chimiques de Rennes, CNRS UMR 6226, Universit\'e Rennes 1, 263 Avenue G\'en\'eral Leclerc, 35700 Rennes, France}


%% *-----------------------------------------------------------------------------------------*

%% Place below other \usepackage{ ... }, if you need other packages.
%% See http://www.tug.org/texlive/doc.html for a description of available packages.

%% The macros below will change the page head and foot.
%% Please, do not modify the content of the \fancyhead macro nor the \fancyfoot line.
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhead[C]{{\footnotesize \textit{HRMS, 28th Colloquium, Dijon, France,
  Aug. 28 - Sept. 1, 2023}}}
\fancyfoot[C]{}
\renewcommand{\headrulewidth}{0.6pt}
\renewcommand{\footrulewidth}{0.6pt}

%% The hyperref package allows to include hyperlinks in a document.
%% See the instructions for abstract submission for more details.
%% WARNING: Make sure that this package comes LAST since it re-defines many LaTeX macros.
\usepackage[colorlinks=true,urlcolor=blue,linkcolor=blue,citecolor=blue]{hyperref}
\voffset -.65 cm

%% *-----------------------------------------------------------------------------------------*



\category {2,8}
\begin{document}

\maketitle

\index{VUV spectroscopy}
\index{Ab initio}
\index{C_4H_3N}
\index{C_5H_2N}
\index{C_4H_5N}

Our group has been studying the VUV photoionization of interstellar molecules for a decade, focusing on so-called interstellar complex organic molecules (iCOMs) 
which usually contain more than 5 atoms. Here we study the photoionization dynamics and the dissociative photoionization, via mass-selected threshold photoelectron
spectroscopy (TPES) and velocity map imaging (VMI). To derive photoionization and dissociative photoionization rates for astrophysical applications, 
ionization and dissociative photoionization cross sections can be estimated to better than an order of magnitude. 
Here, we used the DELICIOUS 3 spectrometer installed as a permanent end station on the DESIRS beamline at the Synchrotron SOLEIL facility in France, to study a series 
of interstellar nitriles; all of which have been observed in molecular clouds. These are the following: 1) methyl cyano acetylene (MCA; \chem{C_4H_3N}), 
2) Vinyl cyano acetylene (VCA; \chem{C_5H_3N}) and 3) 2-cyano propene (2CP; \chem{C_4H_5N}). MCA has been detected since 1984 by several groups
\footnote{N.W. Broten, J.M. MacLeod, L.W. Avery, W.M. Irvine, B. Hoglund, P. Friberg, and A. Hjalmarson, Astrophys. J. 1984, 276, L25-L29.}, whereas VCA and 2CP 
have been detected only in 2021\footnote{K.L.K. Lee, R.A. Loomis, A.M. Burkhardt, I.R. Cooke, C. Xue, M.A. Siebert, C.N. Shingledecker, A. Remijan, S.B. Charnley, M.C. McCarthy, B.A. McGuire, 
Astrophys. J. Lett. 2021, 908, L11.}$^{,}$\footnote{J. Cernicharo, R. Fuentetaja, C. Cabezas, M. Agundez, N. Marcelino, B. Tercero, J. R. Pardo, P. de Vicente, Astron. Astrophys. 2022, 663, L5.}. 
Detections are all in the Taurus Molecular Cloud (TMC-1). We will present preliminary results on photoionization mass spectra and slow photoelectron spectra of parent and 
fragment ions, from the respective ionization energies up to 15.5 eV. This energy range suffices to derive accurate photo rates in cold molecular clouds due to cosmic ray 
ionization. Calculations are performed too in order to rationalize the chemical structure of the formed fragments. Astrophysical implications of our study will be discussed.\\
This work was supported by the Programme National de Physique et Chimie du Milieu Interstellaire (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES.

       
\end{document}
