Response of an electrodeless quartz crystal microbalance in gaseous phase and monitoring adsorption of iodine vapor on zeolitic-imidazolate framework-8 film

摘要

In this work, the response of an electrodeless quartz crystal microbalance (EL-QCM) in gaseous phase was investigated by an impedance analysis method. The influence of the gap size, are, position and shape of the electrodes on the resonant and equivalent circuit parameters of the EL-QCM was analyzed and discussed in a modified Butterworth-Van Dyke model. Compared with a conventional QCM, the intensity of resonant peak in EL-QCM is reduced remarkably. An EL-QCM has a quality factor in the order of 105 even at an air gap of 1 cm, ensuring an excellent frequency stability of this type of sensor. The excitation electrode can be mounted beside of the center of the quartz disc or outside the detection cell if needed, which offers the convenience in combination with mass and optical measurements. As an example of applications, two EL-QCM sensors in a parallel combination were used to monitor the adsorption processes of iodine vapor on quartz surface and zeolitic-imidazolate framework-8 (Z1F-8) film. The transfer process of iodine between two ZIF-8 films was investigated by the series combination of two EL-QCM sensors.