From plasmon-mediated molecular spectroscopy to molecular quantum technologies

par Tomas Neuman

Institut de physique et de chimie des Matériaux de Strasbourg (IPCMS)

Vibrational, electronic, and spin excitations in molecules can identify molecules in spectroscopy, but also play a role in molecular chemical reactivity, or find technological applications e.g. in superresolution microscopy or infrared-to-optical transduction. Recently, excitations in single molecules and molecular networks have been proposed to serve as physical platforms for qubits or for nanoscale sources of non-classical photon states. To fully take advantage of the molecular platforms it is therefore necessary to elucidate how molecular excitations can be detected, engineered, and controlled, especially on the single- or a few-molecular scale. I will discuss how nanoscale metallic structures supporting collective electronic excitations - plasmons - can be used to enhance the interaction between photons and molecular excitations and thus detect and control them. I will show that plasmon-enhanced infrared and optical vibrational spectroscopies or electroluminescence enhanced by effective plasmonic cavities formed in tunneling metallic gaps can be used to detect and manipulate molecular states, or break well-established spectroscopic selection rules. Full understanding of the plasmon-mediated light-matter interactions also enables novel spectroscopic methods exploiting the correlated information about transport and optical properties of molecules. A particular example of the electroluminescence spectroscopy in scanning tunneling microscope used to elucidate the tautomerization dynamics in free-base phthalocyanine molecules will be discusse. Finally, I will elaborate on the potential of molecules for quantum technologies and the role of plasmon-mediated molecular spectroscopy in this field.

Présentation du séminaire sur le site de l'ISMO