A semi-microscopic model for the low-energy photodisintegration of the 9 Be nucleus is constructed, and the experimental data are analyzed with its help. The older radioactive isotope data are supported by this analysis. The theoretical photodisintegration cross section is derived. The astrophysical rates for the reaction α + α + n → 9 Be+γ and the reverse photodisintegration of 9 Be are calculated. The new reaction rate for α + α + n → 9 Be+γ is compared with previous estimations.

An analytical expression for the E1 strength function for two-neutron halo nuclei is derived in a three-body model. Yukawa type wavefunctions for the ground state and threebody plane waves for the final state were used. The expression reproduces the shape and the position of the maximum of the experimental strength function for 11 Li well. It is shown that the exact expression can be approximated over a large energy range with a simple function by introducing an effective two-neutron separation energy. This provides a theoretical approach for quick estimates of the E1 strength function for two-body halo nuclei.

We report, for the first time, to the best of our knowledge, a femtosecond mode-locked Fe:ZnSe laser. Passive mode locking is implemented using graphene as a saturable absorber. The laser operates at 4.4 µm with a repetition frequency of 100 MHz and 415 mW output power pumped by a fiber 7 W Er:ZBLAN laser. The pulse duration of about 732 fs is retrieved from the first-order autocorrelation function. Additionally, we observe pulsed nanosecond oscillation under continuous-wave pumping and strong amplitude modulation caused by Kerr self-focusing. This Letter fills the gap in operating regimes of Fe:ZnSe lasers and paves the way for the development of powerful ultrafast high-repetition-rate mid-IR sources for the most advanced fields of science.

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We demonstrate a first-of-its-kind efficient amplification of a broadband tunable (from 3.8 to 4.8 µm) mid-IR femtosecond seed pulse generated from a AgGaS2-based optical parametric amplifier pumped by a Cr:forsterite laser in a multi-pass Fe2+:ZnSe amplifier optically pumped by a solid-state nanosecond Cr:Yb:Ho:YSGG laser. A total gain of 2000 for an input seed energy of 40 nJ has been obtained. The magnitude of the output energy reaches 80 µJ at a pulse duration of 200 fs.