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We present a frequency domain, AOM-based pulse shaper that utilizes Brewster prisms rather than the current standard of gratings. In doing so, we demonstrate a three-fold increase in efficiency and the ability to compensate for temporal dispersion created by the acousto-optic modulator that filters the pulse spectrum. The shaper is tested between the wavelengths of 520-660 and 840-1170 nm, creating sub-50 fs pulses for each, and used to collect a 2D white-light spectrum of a thin film of semiconducting carbon nanotubes.

 

The STEM Center at Sam Houston State University (SHSU) has received funding from the National Science Foundation (NSF - IUSE) and was established in 2017. The STEM Center seeks to increase the number and quality of STEM graduates by establishing a strong foundation for learning using innovative teaching practices, supporting students in finding research and internship opportunities, and building lifelong skills needed for advancement and leadership in STEM careers. The center is in one of the STEM buildings with two fully equipped classrooms and office space for full-time staff members. The center staff collaborates with university-wide programs to promote STEM education and contribute to the university’s quality enhancement plan (QEP). The paper shares details regarding faculty and student involvement, the development of preparatory courses, institution-wide resources, and student outcomes from the project with the academic community. 

We present two-dimensional white-light spectroscopy (2DWL) measurements of binary and ternary bulk heterojunctions of the polymer donor PM6 mixed with state-of-the-art nonfullerene acceptors Y6 or IT4F. The ternary film has a shorter lifetime and faster spectral diffusion than either of the binary films. 2D line shape analysis of the PM6 ground state bleach with a Kubo model determines that all three films have similar amplitudes of fluctuations (Δ = 0.29 fs–1) in their transition frequencies, but different relaxation times (ranging from 102 to 24 fs). The ternary film exhibits faster dynamics than either of the binary films. The short lifetime of the ternary blend is consistent with increased photoexcitation transfer and the fast frequency fluctuations are consistent with structural dynamics of aliphatic side chains. These results suggest that the femtosecond fluctuations of PM6 are impacted by the choice of the acceptor molecules. We hypothesize that those dynamics are either indicative, or perhaps the initial source, of structural dynamics that ultimately contribute to solar cell operation. 

ABSTRACT We present a hyperspectral cube of the Crab Nebula obtained with the imaging Fourier transform spectrometer SITELLE on the Canada–France–Hawaii telescope. We describe our techniques used to deconvolve the 310 000 individual spectra ($R = 9\, 600$) containing Hα, [N ii] λλ6548, 6583, and [S ii] λλ6716, 6731 emission lines and create a detailed 3D reconstruction of the supernova (SN) remnant (SNR) assuming uniform global expansion. We find that the general boundaries of the 3D volume occupied by the Crab are not strictly ellipsoidal as commonly assumed, and instead appear to follow a ‘heart-shaped’ distribution that is symmetrical about the plane of the pulsar wind torus. Conspicuous restrictions in the bulk distribution of gas consistent with constrained expansion coincide with positions of the dark bays and east–west band of He-rich filaments, which may be associated with interaction with a pre-existing circumstellar disc. The distribution of filaments follows an intricate honeycomb-like arrangement with straight and rounded boundaries at large and small scales that are anticorrelated with distance from the centre of expansion. The distribution is not unlike the large-scale rings observed in SNRs 3C 58 and Cassiopeia A, where it has been attributed to turbulent mixing processes that encouraged outwardly expanding plumes of radioactive 56Ni-rich ejecta. These characteristics reflect critical details of the original SN of 1054 CE and its progenitor star, and may favour a low-energy explosion of an iron-core progenitor. We demonstrate that our main findings are robust despite regions of non-homologous expansion driven by acceleration of material by the pulsar wind nebula.