The reaction microscope (REMI) at the Shanghai soft x-ray free electron laser for AMO science consists of a supersonic gas injection system, a spectrometer, and detectors with a data acquisition system. The pump-probe scheme will be provided with the synchronization of the external optical laser to the XFEL pulse. An Even-Lavie type high temperature pulsed valve will be implemented to further extend from gas sample to liquid or even volatile biomolecules in solid states. By measuring the time of flight and impact positions of ions and electrons on their corresponding detector, three-dimensional momentum vectors can be reconstructed in a coincidence manner. Momentum resolutions of ions and electrons with 0.11 a.u. can be achieved.
The composite velocity imaging spectrometer (CpVMI) is one of two novel instruments at the Shanghai soft x-ray free electron laser for AMO science. The CpVMI consists of an ultrasonic molecular beam generation device, an electron velocity imaging system, a three-dimensional ion momentum imaging system and a vacuum system. The molecular beam or cluster beam generated by the ultrasonic molecular beam device enters the reaction chamber and interacts with the x-ray free electron laser or optical laser pulses, and then the produced electrons and ions fly towards the electron and ion imaging systems to obtain their momentum and energy information. The pump-probe scheme can be supported with in-coupling of x-ray with the external optical laser. The scientific objectives are to reveal the quantum characteristics such as strong field nonlinear phenomena, ultrafast dynamics of photoexcited systems, nanoplasma formation and evolution, and photoelectron diffraction and so on. Compared with the existing advanced spectrometers in the world, a major feature of the CpVMI is that the dynamical measurement range of electronic kinetic energy upgrades from 100 eV up to 1000 eV with a higher energy resolution, which provides a powerful observation capability for the related physical and chemical processes.