The absorption spectrum and photodissociation dynamics of the hydroxymethyl radical via its two lowest excited electronic states, 3s and 3p x , are investigated in a supersonic molecular beam by the depletion, resonance enhanced multiphoton ionization, and photofragment yield spectroscopy methods. The measured origins of the electronic transitions to the 3s and 3 p x states agree with the most recent ab initio calculations. The vibronic bands of the 2 2 AЈ(3p x)←1 2 AЉ transition are much broader than those of the transition terminating in the 2 2 AЉ(3p z) state, while the transition to the 1 2 AЈ(3s) state appears structureless. The investigation of the deuterated analog CH 2 OD shows that near the onset of the transition to the 3s state, only the O-D bond fission pathway is important, while both H and D products are detected following excitation to the 3p x state. The progressive broadening of the absorption features from the uppermost 3p z to the lowest 3s excited state is explained based on recent calculations of surface couplings to lower electronic states. These couplings also control the photodissociation dynamics and the reaction outcomes.

Nanocatalysts based on Fenton or Fenton‐like reactions for amplification of intracellular oxidative stress has become a frontier research area of tumor precise therapy. However, the major translational challenges are low catalytic efficiency, poor biocompatibility, and even potential toxicities. Here, a Ti‐based material with excellent biocompatibility is proposed for cancer treatment. The nonoxidized MXene‐Ti3C2Tx quantum dots (NMQDs‐Ti3C2Tx) are successfully prepared by a self‐designed microexplosion method. Surprisingly, it has an apparent inhibitory and killing effect on cancer cells, and excellent biocompatibility with normal cells. Moreover, the suppression rate of NMQDs‐Ti3C2Tx on xenograft tumor models can reach 91.9% without damaging normal tissues. Mechanistically, the Ti3+ of NMQDs‐Ti3C2Tx can react with H2O2 in the tumor microenvironment and high‐efficiently produce excessive toxic hydroxyl radicals to increase tumor microvascular permeability to synergistically kill cancer cells. This work should pave the way for tumor catalytic therapy applications of Ti‐based material as a promising and safer route.

In this paper, a facile synthetic route of cobalt ferrite nanocrystals with narrow size distribution was reported.The key feature of this method involved a very rapid mixing of reducible metal cations with sodium borohydride and simultaneous reduction in a colloid mill, which is followed by a slow oxidation in a separate hydrothermal treatment. The microstructural and magnetic characteristics of the materials were characterized by powder X-ray diffraction (XRD), chemical analysis, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), Mo ¨ssbauer spectroscopy, and magnetometry. The results unambiguously indicated that the obtained products consisted of CoFe 2 O 4 nanocrystals with good monodispersity and high stoichiometry and that, especially, a 9 nm sample exhibited room-temperature superparamagnetism. The formation mechanism of nanocrystals was proposed. It is believed that the extreme forces, to which the nucleation mixture of metallic cobalt and iron obtained with a very short time was subjected in the colloid mill, prevented aggregation of the newly formed metal nuclei. Consequently, when the resulting metal nuclei were oxidized slowly in a separate hydrothermal treatment, CoFe 2 O 4 nanocrystals with narrow size range were obtained.

An investigation of phase distribution demonstrated that PCDTBT was embedded in PTB7-Th and ITIC, and hence introduced dual FRET effects in the resulting ternary system.

Photodissociation studies of the CH2OD radical in the region 28,000-41,000 cm(-1) (357-244 nm), which includes excitation to the 3s, 3p(x), and 3p(z) states, are reported. H and D photofragments are monitored by using resonance-enhanced multiphoton ionization (REMPI) from the onset of H formation at approximately 30,500 cm(-1) to the origin band region of the 3pz(2A")<--1 2A" transition at 41,050 cm(-1). Kinetic energy distributions P(ET) and recoil anisotropy parameters as a function of kinetic energy, beta(eff)(ET), are determined by the core sampling technique for the channels producing H and D fragments. Two dissociation channels are identified: (I) D+CH2O and (II) H+CHOD. The contribution of channel II increases monotonically as the excitation energy is increased. Based on the calculations of Hoffmann and Yarkony [J. Chem. Phys. 116, 8300 (2002)], it is concluded that conical intersections between 3s and the ground state determine the final branching ratio even when initial excitation accesses the 3px) and 3pz states. The different beta(eff) values obtained for channels I and II (-0.7 and approximately 0.0, respectively) are attributed to the different extents of out-of-plane nuclear motions in the specific couplings between 3s and the ground state (of A' and A'' symmetry, respectively) that lead to each channel. The upper limit to the dissociation energy of the C-H bond, determined from P(ET), is D0(C-H)=3.4+/-0.1 eV (79+/-2 kcal/mol). Combining this value with the known heats of formation of H and CH2OD, the heat of formation of CHOD is estimated at DeltaHf(0)(CHOD)=24+/-2 kcal/mol.