Hydrogen is an element of fundamental importance for energy but hard to quantify in bulk materials. Neutron radiography was used to map in situ loss of elemental hydrogen from beech tree wood samples during pyrolysis. The samples consisted of three wood cylinders (finished dowel or cut branch) of approximately 1 cm in length. The samples were pyrolyzed under vacuum in a furnace vessel that was placed inside a cold neutron imaging beamline using a temperature ramp of 5 °C/min from ambient up to 400 °C. Neutron radiographs with exposures of 30 s were sequentially recorded with a charge-coupled device over the course of the experiment. Relative absorbance/scattering of the neutron beam by each sample was based on intensity (or brightness) values as a function of pixel position. The much larger neutron cross section for hydrogen compared to carbon and oxygen enables almost direct conversion of neutron attenuation into sample hydrogen content for each time step during the pyrolysis experiment. Target and vessel temperatures were recorded concurrently with collection of the radiographs so that changes could be directly correlated to different states of pyrolysis. The most visible change appeared at the initial phase of the 400 °C plateau as evidenced by strong hydrogen loss and primarily diametric shrinking of the samples. The loss of elemental hydrogen between initial and final states of pyrolysis was estimated to be about 70%.

氢是一种对能源至关重要的元素，但在散装材料中却很难量化。中子射线照相术用于原位成像热解过程中山毛榉木样品中元素氢的损失。样品由三个长度约为1厘米的木圆柱（成品木钉或切好的树枝）组成。样品在真空条件下在炉容器中热解，该炉容器放置在冷中子成像束线内部，温度从周围温度升至5°C / min至最高400°C。在实验过程中，用电荷耦合器件顺序记录了曝光时间为30 s的中子射线照相。每个样品对中子束的相对吸收/散射是基于强度（或亮度）值作为像素位置的函数。与碳和氧相比，氢的中子截面要大得多，因此在热解实验的每个时间步中，中子衰减几乎可以直接转换为样品中的氢含量。在收集射线照片的同时记录目标温度和容器温度，以便将变化直接与热解的不同状态相关。最明显的变化出现在400°C平稳期的初始阶段，这是由强烈的氢损失和样品的主要径向收缩所证明的。热解的初始状态和最终状态之间元素氢的损失估计约为70％。