Femtosecond laser pulses lasting only a few optical periods hold the potential for probing and manipulating the electronic degrees of freedom within matter. However, the generation of high-contrast, few-cycle pulses in the high power limit still remains nontrivial. In this Letter, we present the application of ammonium dihydrogen phosphate (ADP) as an optical medium for compensating for the higher-order dispersion of a carrier-envelope stable few-cycle waveform centered at 735 nm. The ADP crystal is capable of removing the residual third-order dispersion present in the spectral phase of an input pulse, resulting in near-transform-limited 2.9 fs pulses lasting only 1.2 optical cycles in duration. By utilizing these high-contrast, few-cycle pulses for high-harmonic generation, we are able to produce nanojoule-scale, isolated attosecond pulses.
Attosecond probing of core-level electronic transitions provides a sensitive tool for studying valence molecular dynamics with atomic, state, and charge specificity. In this report, we employ attosecond transient absorption spectroscopy to follow the valence dynamics of strong-field initiated processes in methyl bromide. By probing the 3 d core-to-valence transition, we resolve the strong field excitation and ensuing fragmentation of the neutral σ * excited states of methyl bromide. The results provide a clear signature of the non-adiabatic passage of the excited state wavepacket through a conical intersection. We additionally observe competing, strong field initiated processes arising in both the ground state and ionized molecule corresponding to vibrational and spin-orbit motion, respectively. The demonstrated ability to resolve simultaneous dynamics with few-femtosecond resolution presents a clear path forward in the implementation of attosecond XUV spectroscopy as a general tool for probing competing and complex molecular phenomena with unmatched temporal resolution.
Hyperthermia is a type of medical modality for cancer treatment using the biological effect of artificially induced heat. Even though the intrinsic effects of elevated body temperature in cancer tissues are poorly understood, increasing the temperature of the body has been recognized as a popular therapeutic method for tumorous lesions as well as infectious diseases since ancient times. Recently accumulated evidence has shown that hyperthermia amplifies immune responses in the body against cancer while decreasing the immune suppression and immune escape of cancer. It also shows that hyperthermia inhibits the repair of damaged cancer cells after chemotherapy or radiotherapy. These perceptions indicate that hyperthermia has potential for cancer therapy in conjunction with immunotherapy, chemotherapy, radiotherapy, and surgery. Paradoxically, the anticancer effect of hyperthermia alone has not yet been adequately exploited because deep heating techniques and devices to aggregate heat effects only in cancer tissues are difficult in practical terms. This review article focuses on the current understanding concerning cancer immunity and involvement of hyperthermia and the innate and adoptive immune system. The potential for combination therapy with hyperthermia and chemotherapy, radiotherapy, and surgery is also discussed. Key words:Hyperthermia, cancer immunity, chemosensitizer, radiosensitizer, combination cancer therapy, hyperthermic intraoperative peritoneal chemotherapy ABSTRACTArticle history:
Electronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized 1B2u (ππ*) (S2) and 1B3u (nπ*) (S1) states, the participation of the optically dark 1Au (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computations. Despite 1Au (nπ*) and 1B3u (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The 1Au (nπ*) state is populated in 200 ± 50 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.
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