Temporal changes in carrier relaxations, magnetic switching, and biological structures are known to be in the order of ns. These phenomena can be typically measured by means of an optical-pump & electron-probe method using an electron microscope combined with a pulsed electron source. A photoemission-type pulsed electron gun makes it possible to obtain a short-pulsed electron beam required for high temporal resolution. On the other hand, spatial resolution is restricted by the brightness of the pulsed electron gun used in electron microscopes when a low brightness electron source is used and an irradiation current larger than a certain value is required. Thus, we constructed a prototype pulsed electron gun using a negative electron affinity (NEA) photocathode for time-resolved measurement using a scanning electron microscope (SEM) with high spatiotemporal resolution. In this study, a high-speed detector containing an avalanche photodiode (APD) was used to directly measure waveforms of the pulsed electron beam excited by a rectangular-shape pulsed light with a variable pulse duration in the range of several ns to several μs. The measured waveforms were the same rectangular shape as incident pulsed excitation light. The maximum peak brightness of the pulsed electron beam was 4.2×10⁷ A/m²/sr/V with a pulse duration of 3 ns. This value was larger than that of the continuous electron beam (1.6 × 10⁷ A/m²/sr/V). Furthermore, an SEM image with image sharpness of 6.2 nm was obtained using an SEM equipped with a prototype pulsed electron gun at an acceleration voltage of 3 kV.

载流子弛豫、磁开关和生物结构的时间变化已知为 ns 级。这些现象通常可以通过光泵和电子探针方法使用电子显微镜与脉冲电子源相结合来测量。光电发射型脉冲电子枪使得获得高时间分辨率所需的短脉冲电子束成为可能。另一方面，当使用低亮度电子源并且需要大于一定值的照射电流时，空间分辨率受到电子显微镜中使用的脉冲电子枪的亮度的限制。因此，我们使用负电子亲和性 (NEA) 光电阴极构建了原型脉冲电子枪，使用具有高时空分辨率的扫描电子显微镜 (SEM) 进行时间分辨测量。在这项研究中，包含雪崩光电二极管 (APD) 的高速探测器用于直接测量由矩形脉冲光激发的脉冲电子束的波形，脉冲持续时间在几纳秒到几微秒的范围内。测量的波形是与入射脉冲激发光相同的矩形。脉冲电子束最大峰值亮度为4.2×10 包含雪崩光电二极管 (APD) 的高速检测器用于直接测量由矩形脉冲光激发的脉冲电子束的波形，脉冲持续时间在几纳秒到几微秒的范围内。测量的波形是与入射脉冲激发光相同的矩形。脉冲电子束最大峰值亮度为4.2×10 包含雪崩光电二极管 (APD) 的高速检测器用于直接测量由矩形脉冲光激发的脉冲电子束的波形，脉冲持续时间在几纳秒到几微秒的范围内。测量的波形是与入射脉冲激发光相同的矩形。脉冲电子束最大峰值亮度为4.2×10⁷ A/m ² /sr/V，脉冲持续时间为 3 ns。该值大于连续电子束的值（1.6×10 ⁷ A/m ² /sr/V）。此外，使用配备有原型脉冲电子枪的 SEM 在 3 kV 加速电压下获得图像清晰度为 6.2 nm 的 SEM 图像。