Welcome to the Boulesbaa Ultrafast Sciences Group at
California State University Northridge

Laser Lab

We are a multidisciplinary group. Our research interests range from Physics, Chemistry, Biochemistry, to Engineering. We use the state of the art spectroscopy and microscopy techniques to investigate ultrafast phenomena that take place not only in small dimensions (Angström and Nanometer scales) but, also in ultrashort time scales; FemtoSecond (1 fs= one millionth of one billionth of a second). To do this; we use a Ti:Sa femtosecond laser amplifier that provides pulses as short as 35 fs. The overarching goal of our research program is to understand, and possibly control, the flow of energy (electronic and vibrational) and electric charges within nanomaterials and through chemical bonds.

We study a broad range of nanomaterials, including quantum dots (QDs), plasmonics, two-dimensional transition metal dichalcogenides (2D-TMDs), and hybrid organic/inorganic perovskites. For molecular systems, we are particularly interested in studying water and DNA base-pair molecules. Our laser spectroscopy capabilities include emission lifetime decay and transient absorption from the UV to mid infrared, with a sub-50 fs temporal resolution.

Photoluminescence map and pump-probe dynamics

(Left panel) Photoluminescence (PL) map of a single crystal of tungsten disulfide (WS2) atomically thin monolayer (~7 ångström thickness ) excited at 3.1 eV and the emission was averaged around 2 eV photon energies.
(Right panel) Ultrafast pump-probe dynamics measured from the 2D-WS2 monolayer (shown in the left panel) following a 45 fs short pump at 3.1 eV photon energy. The two peaks around 2 eV and 2.4 eV indicate the exciton depletion signals of XA and XB transitions, respectively.