Support for young scientists from all over the world
Doctoral projects
© J. Feis et al., Phys. Rev. Lett.

Helic­ity Preserv­ing Cavity for Circu­lar Dichro­ism Enhancement

Philip Scott – Hector Fellow Martin Wegener

Most modern drugs are made up of one handed­ness of a chiral molecule (one enantiomer). In many cases, depend­ing on the handed­ness of the enantiomer, the drug could have either benefi­cial or harmful effects, thus is it desir­able to be able to detect the handed­ness. Circu­lar dichro­ism (CD) spectroscopy can differ­en­ti­ate between the handed­ness due to differ­en­tial absorp­tion of circu­larly polarised light but suffers from weak signals; there­fore, a method that can enhance the signal is desired.

Being able to detect the handed­ness of an enantiomer is impor­tant so that a dug consist­ing of the wrong enantiomer is not given to a patient, which could result in harmful effects instead of helpful effects. A method that can differ­en­ti­ate between the handed­ness of enantiomers is CD spectroscopy, but this suffers from weak signals from the molecules and thus requires long sampling times and large sample sizes. Because of the weak signals from CD spectroscopy, one would desire for a solution that can improve this signal without chang­ing the sample size.

In the project super­vised by Hector Fellow Martin Wegener, I will use techniques such as RF-sputter­ing and litho­g­ra­phy to fabri­cate the CD enhanc­ing cavity proposed by the Rockstuhl and Wegener groups at KIT. The cavity will need to be fabri­cated in accor­dance to three design require­ments. It must be achiral, helic­ity preserv­ing and have a large field enhance­ment over a large area. The design for the cavity consists of two silicon disk arrays that make use of the first diffrac­tion order to produce large helic­ity preserv­ing modes whereas a conven­tional cavity would flip the helic­ity of the light that would lower the CD signal.

I will also design and build an exper­i­men­tal setup to test the enhance­ment values of the cavity. The exper­i­men­tal setup must be able to vary the size of the cavity and the align­ment of the two arrays to not disobey the design condi­tion and have a microflu­idic chamber for the molecules to flow through.

Helicity Preserving Cavity for Circular Dichroism Enhancement

Figure descrip­tion: 3D model of the silicon disk cavity with helic­ity preserv­ing modes. (J. Feis et al., Phys. Rev. Lett., submit­ted. (2019), with permission)

Philip Scott

Karlsruhe Insti­tute of Technology

Betreut durch

Prof. Dr.

Martin Wegener

Physics & Engineering

Disziplinen Martin WegenerHector Fellow since 2008