December 2006: First optical experiments in the pulsed magnet at 52T

Figure 1 Photoluminescence setup in the pulsed magnet. The excitation beam is delivered by an argon-ion laser (514.5 nm, 2W) and with a fiber guided to the sample. The luminescence is collected with a multimode fiber, dispersed and recorded by a LN cooled CCD camera.

CdSe quantum rods (QRs) are a system in which carriers are confined in three dimensions, which implicates that their energy levels are discrete. To investigate the energy levels, polarised photoluminescence is used. In a magnetic field the levels shift to lower and higher energy, depending on the spin of the particles. This effect we have measured in pulsed magnetic fields up to 52 T. A thin film sample of CdSe QRs has been made by drop casting a high concentration solution of QRs in toluene on a clean plate of silicon. The QRs were optically excited by green 514.5 nm laser light that was delivered to the sample by a multimode fibre. The polarised photoluminescence of the QRs (T = 4.2 and T = 1.2 K) was collected by a separate fibre. The light was spectrally resolved and recorded with a liquid nitrogen cooled CCD camera. Spectra were acquired every 2 milliseconds. The acquisition was triggered by a TTL pulse generated by the capacitor bank.

This result shows that the optical setup in the pulsed field facility is now fully operational and ready to use for experiments.

Figure 2: Black solid line: magnetic field shape of a pulse with a maximum field of 52 T. The pulse is generated by a LN cooled wire wound coil which is driven by a 2 MJ 16 kV capacitor bank. The blue solid line indicates the exposure time of the CCD camera. Inset: three different polarised photoluminescence spectra of CdSe QRs at different magnetic fields.