X-ray free-electron lasers promise diffractive imaging of single molecules and nanoparticles with atomic spatial resolution. This relies on the averaging of millions of diffraction patterns of identical particles, which should ideally be isolated in the gas phase and preserved in their native structure. Here, we demonstrated that polystyrene nanospheres and Cydia pomonella granulovirus can be transferred into the gas phase, isolated, and very quickly shock-frozen, i.e., cooled to 4 K within microseconds in a helium-buffer-gas cell, much faster than state-of-the-art approaches. Nanoparticle beams emerging from the cell were characterized using particle-localization microscopy with light-sheet illumination, which allowed for the full reconstruction of the particle beams, focused to < 100   μ m , as well as for the determination of particle flux and number density. The experimental results were quantitatively reproduced and rationalized through particle-trajectory simulations. We propose an optimized setup with cooling rates for particles of few-nanometers on nanosecond timescales. The produced beams of shock-frozen isolated nanoparticles provide a breakthrough in sample delivery, e.g., for diffractive imaging and microscopy or low-temperature nanoscience.

中文翻译：

---

激冷，隔离，生物和人工纳米粒子的受控光束。

X射线自由电子激光器有望以原子空间分辨率对单分子和纳米粒子进行衍射成像。这依赖于相同颗粒的数百万个衍射图的平均，理想情况下，应在气相中将其分离并保留其天然结构。在这里，我们证明了聚苯乙烯纳米球和Cydia pomonella颗粒病毒可以转移到气相中，分离并非常快速地冷冻，即在氦缓冲气体池中在几微秒内冷却至4 K，比状态快得多。最先进的方法。使用带有光片照明的粒子定位显微镜对从细胞中发出的纳米粒子束进行表征，从而可以完全重建粒子束，聚焦到<100μm，以及用于确定粒子通量和数密度的方法。通过粒子轨迹模拟对实验结果进行了定量再现和合理化。我们提出了一种优化的设置，在纳秒级的时间尺度上为几纳米的颗粒提供了冷却速率。产生的激冷分离纳米粒子束在样品输送方面提供了突破，例如，用于衍射成像和显微镜或低温纳米科学。