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A complementary measurement method based on a home-built double-sided velocity map imaging setup is introduced. This method can simultaneously obtain time-resolved photoelectron imaging and fragment ion imaging. It has been successfully applied to investigate the ultrafast dynamics of the second singlet electronically excited state (S2) in m-xylene. Time-resolved photoelectron and ion signals derived from the initial populated S2 state are tracked following two-photon absorption of a pump pulse. Time-of-flight mass spectra (TOFMS) show that there are dominant parent ions and one fragment ions with methyl loss during such a process. According to the measured photoelectron images and fragment ions images, transient kinetic energy distributions and angular distributions of the generated photoelectrons and fragments are obtained and analyzed. Compared to stand-alone photoelectron imaging, the obtained fragment ion imaging is powerful for further understanding the mechanisms especially when the dissociation occurs during the pump-probe ionization. Two competing channels intersystem crossing T3 ← S2 and internal conversion S1 ← S2 are attributed to the deactivation of the S2 state. A lifetime of ~50 fs for the initially excited S2 state, of ~276 fs for the secondary populated S1 state, and of 5.76 ps for the T3 state is inferred. [ABSTRACT FROM AUTHOR]

In the journey to obtain well-crystallized mixed tin (Sn)-lead (Pb) iodide perovskite films for solar cell application, great difficulties have been presented due to very different crystallization rates between Sn- and Pb-based perovskite components. Herein, we report a new strategy to grow highly crystallized Sn-Pb perovskite (FA0.7MA0.3Sn0.5Pb0.5I3) for perovskite solar cells (PSCs). An iso-pentylammonium tetrafluoroborate ([PNA]BF4) ionic salt layer is introduced on top of poly(3,4-ethylenedioxythiophene)-poly-(styrenesulfonate) (PEDOT:PSS) to function as anchoring agent to bond Pb2+ to the surface of PEDOT:PSS, which can facilitate a quick crystallization of Pb-containing perovskite components and homogeneously distribute Sn/Pb elements inside the perovskite film in a vertical direction, uncovered by focused ion beam time-of-flight secondary ion mass spectrometry. Additionally, greatly reduced surface residual stress was also confirmed by X-ray diffraction. Lastly, these ionic salt molecules are able to encapsulate the acidic and hygroscopic surface of PEDOT:PSS to further ensure device stability. As a result, our strategies enabled a champion PCE of 20.11% for mixed Sn-Pb PSCs with improved thermal stability at 85 °C over 240 hours and shelf storage stability over 1200 hours. This work provides a new strategy to regulate the crystallization process of mixed Sn-Pb perovskites for both high performance and stability. [ABSTRACT FROM AUTHOR]

Background/Aims: Macrophage inflammatory protein-2 (MIP-2), a type of leukocyte chemokine, is primarily produced by macrophages, and levels increase significantly in early inflammation. However, the precise biological functions and mechanisms of MIP-2 in the development of inflammation remain unclear. The purposes of the present study were to investigate the role of MIP-2 in inflammation induced by lipopolysaccharide (LPS) in vitro and to determine the possibility of blocking the high mobility group box 1 (HMGB1) signalling pathway via MIP-2 inhibition. Methods: Macrophage cells (RAW264.7, U937 and THP-1 cells) were divided into control and treatments groups. Expression levels of interleukin-6 (IL-6), interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), HMGB1, chemokine (C-C motif) ligand-2 (Ccl-2), Toll-like receptor-4 (TLR-4), inducible nitric oxide synthase (iNOS), phosphorylated MAPKs (p38, ERKs, JNKs), PI3K/Akts, JAKs/STAT3, IκB, and cytoplasmic and nuclear NF-κB p65 in RAW264.7 cells were detected by qRT-PCR, enzyme-linked immunosorbent assay (ELISA) or western blot assays. Results: mip-2 siRNA and an anti-MIP-2 antibody significantly reduced the expression levels of Ccl-2, TLR-4, iNOS, IL-6, IL-1β, HMGB1, and TNF-α in RAW264.7 cells exposed to LPS (P<0.01). Additionally, mRNA expression levels of HMGB1 and TLR-4 in cells treated with LPS+mip-2 siRNA were significantly lower than those in cells treated with LPS alone (P<0.01 or P<0.05). The MIP-2 antibody significantly suppressed activation of p38-MAPK, p-STAT3, and p-Akts and translocation of NF-κB p65 from the cytoplasm to the nucleus in RAW264.7 exposed to LPS (P<0.01 or P<0.05). Conclusion: mip-2 siRNA and the MIP-2 antibody can reduce the inflammatory effects induced by LPS in macrophage cells. The mechanisms may occur through down-regulation of p38-MAPK, STAT3 and Akts phosphorylation and translocation of NF-κB p65. MIP-2 plays an important role in inflammation induced by LPS. [ABSTRACT FROM AUTHOR]

We theoretically investigated the coherent control of Autler-Townes splitting in photoelectron spectroscopy of K2 molecule within an ultrafast laser pulse by solving the time-dependent Schrodinger equation using a quantum wave packet method. It was theoretically shown that we can manipulate the splitting of photoelectron spectroscopy by altering the laser intensity. Furthermore, it was found that the percentages of each peak in photoelectron spectroscopy can be controlled by changing the envelope of the laser pulse. [ABSTRACT FROM AUTHOR]

Bichromatic circularly polarized fields provide a useful tool to probe the ionization dynamics. In this work, we compare the photoelectron momentum distribution in few-cycle bichromatic field of different helicities. The spectral features are analyzed with semiclassical trajectories derived from the strong field approximation. In particular, the interference fringes in momentum distribution are investigated by tracking the ionization time and tunneling exits of released photoelectrons. Different types of trajectories that contribute to the interference fringes are elucidated. [ABSTRACT FROM AUTHOR]

The photodissociation of IBr was investigated by solving the time-dependent Schrödinger equation including the rotational degree of freedom within the wavelength 440–680 nm. Representative samples of 2D slice images and the corresponding total kinetic energy distribution P(E) resulting from photolysis of IBr molecules at ten wavelengths in the range 440–680 nm were obtained. The total kinetic energy distribution P(E) and the P(E) distribution from the respective electronic excited states A, B, C and Y in the range 440–680 nm are also given. Furthermore, the dissociation probability from the respective electronic excited states A, B, C and Y and the branching ratio of Γ(Br*/(Br  +  Br*)) are determined. [ABSTRACT FROM AUTHOR]

The coherent control of interference between dissociating wave packets of the HD+ molecules generated by a pair of time-delayed and phase-locked femtosecond laser pulses is theoretically studied by using the time-dependent quantum wave packet method. The density function in both coordinate and momentum representation are presented and discussed. It is demonstrated that the interference pattern is observed in both coordinate and momentum density functions. The interference undergoes a π-phase shift when the delay time between the two phase-locked femtosecond laser pulses is changed by half an optical period. In particular, the number of interference fringes, the fringe spacing in the R-dependent density distribution |ψ(R)|2, and the modulation period of the energy-dependent distribution of the fragments P(E) can be tuned by two phase-locked femtosecond pulses. [ABSTRACT FROM AUTHOR]