From 3bc8b4451803929d6a47f87a987947c37d95545d Mon Sep 17 00:00:00 2001 From: Blaise Thompson Date: Thu, 12 Apr 2018 21:00:37 -0500 Subject: 2018-04-12 21:00 --- PbSe_global_analysis/methods.tex | 38 -------------------------------------- 1 file changed, 38 deletions(-) delete mode 100644 PbSe_global_analysis/methods.tex (limited to 'PbSe_global_analysis/methods.tex') diff --git a/PbSe_global_analysis/methods.tex b/PbSe_global_analysis/methods.tex deleted file mode 100644 index a62d590..0000000 --- a/PbSe_global_analysis/methods.tex +++ /dev/null @@ -1,38 +0,0 @@ -Quantum dot samples used in this study were synthesized using the hot injection method.\cite{Wehrenberg2002} -Samples were kept in a glovebox after synthesis and exposure to visible and UV light was minimized. -These conditions preserved the dots for several months. -Two samples, Batch A and Batch B, are presented in this study, in an effort to show the robustness of the results. -Properties of their optical characterization are shown in Table \ref{tab:QD_abs}. -The 1S band of Batch A is broader than Batch B, an effect which is usually attributed to a wider size distribution and therefore greater inhomogeneous broadening. - -\begin{table}[] - \centering - \caption{Batch Parameters extracted from absorption spectra. $\langle d \rangle$: average QD diameter, as inferred by the 1S transition energy. } - \label{tab:QD_abs} - \begin{tabular}{l|cc} - & A & B \\ - \hline - $ \omega_{10} \left( \text{cm}^{-1} \right)$ & 7570 & 6620 \\ - $ \text{FWHM} \left(\text{cm}^{-1}\right) $ & 780 & 540 \\ - $ \langle d \rangle \left(\text{nm}\right)$ & 4 & 4.8 \\ - $ \sigma_0 \left( \times 10^{16} \text{cm}^2 \right)$ & 1.7 & 2.9 - \end{tabular} -\end{table} - -The experimental system for the TG experiment has been previously explained.\cite{Kohler2014,Czech2015} -Briefly, two independently tunable OPAs are used to make pulses $E_1$ and $E_2$ with colors $\omega_1$ and $\omega_2$. -The third beam, $E_{2^\prime}$, is split off from $E_2$. The TG experiment utilized here uses temporally overlapped $E_2$ and $E_{2^\prime}$. -Previous ultrafast TG work has characterized the delay of $E_1$ as $\tau_{21}=\tau_2-\tau_1$; to connect the experimental space with the TA measurements, we will report the population delay time between the probe and the pump as $T(=-\tau_{21})$. -Pulse timing is controlled by a motorized stage that adjusts the arrival time of $E_1$ relative to $E_2$ and $E_{2^\prime}$. - -All three beams are focused onto the sample in a BOXCARS geometry and the direction $\vec{k}_1-\vec{k}_2+\vec{k}_{2^\prime}$ is isolated and sent to a monochromator to isolate the $\omega_1$ frequency with $\sim 120 \text{cm}^{-1}$ detection bandwidth. -The signal, $N_{\text{TG}}$, was detected with an InSb photodiode. Reflective neutral density filters (Inconel) limit the pulse fluence to avoid multi-photon absorption. -To control for frequency-dependent changes in pulse arrival time due to the OPAs and the neutral density, a calibration table was established to assign a correct zero delay for each color combination (see supporting information for more details). - -The TA experiments were designed to minimally change the TG experimental conditions. -The $E_{2^\prime}$ beam was blocked and signal in the $\vec{k}_1$ direction was measured. -$E_2$ was chopped and the differential signal and the average signal were measured to define $T_0$ and $T$ needed to compute $\Delta A$. -Just as in TG experiments, the excitation frequencies were scanned while the monochromator was locked at $\omega_m=\omega_1$. -% DK: perhaps leave this part out -%Finally, fluence studies resonant with the 1S band were performed to test for indications of intensity-dependent relaxation. -%These studies showed no indication of accelerated Auger recombination rates (see supporting info). -- cgit v1.2.3