Rayleigh jets are the simplest form of liquid jets. In this method, enough pressure is applied to the sample as it is pushed through a tube in order to come out as a straight jet, that ultimately breaks down into droplets.
The X-rays usually probe the uninterrupted liquid jet but can probe the droplets, as well. When carrying samples, the droplet breakup can be unpredictable and asynchronous with the pulses over time as it is more of a passive process than the active piezo process.
Pros and Cons of Rayleigh Jets
- Easily operated and stable compared to other liquid jet systems
- Simple geometries
- Compatible with vacuum or non-vacuum geometries
- High sample consumption rates (>100 μL/min)
- Jet thickness on the order of the orifice (typically dozens of micrometers or more), which can cause higher background signal
- Inverted driving pressure and liquid flow rates are directly related to the fourth power of the inner diameter of the tubing (e.g., typical diameters are 20-250 μm)
- High vacuum loads
- Prohibitive fluid properties (such as high viscosities)
- Dilute systems (such as chemicals)
- Samples and geometries compatible with recirculation
- Systems that need spatial stability (e.g., correlation experiments)
- Systems with many samples (e.g., you prepare samples in dozens of milliliters to liters)