Design Innovations

Designed for cutting-edge research, yet easy to learn, the LI-6800 is both a powerful research instrument and a remarkable teaching tool that empowers you to ask and answer new questions.

LI-6800 Fluorometer
LI-6800 Fluorometer

Designed for dependable data

You can depend on the LI-6800 every time you turn it on. Precise measurements and highly responsive feedback loops quickly establish target conditions in the sample chamber, providing performance you can trust across samples and experiments.

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Stable measurements

  • High-precision non-dispersive infrared gas analyzers (IRGAs) are stable over time, so you can trust your measurements over the long term.
  • The differential gas exchange system features small volume IRGAs for fast response, advanced optics for dependable measurements, and a patented flow splitting mechanism—technologies that are not available in any other photosynthesis system.
  • IRGAs are open to the sample chamber for fast response and tight coupling of the measurements, controls, and sample responses.
  • Precise leaf temperature measurements accurately represent the leaf temperature at the contact point. Versatile measurement options—one thermocouple, two thermocouples, or energy balance—support numerous sample types and chamber configurations.
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Optimum flow

  • Measurements of primary system flow rate, sample IRGA flow, and reference IRGA flow ensure dependable computed values and that the system is providing air flow at your set point.
  • Secondary flow rate measurements provide real-time leak measurements that can be accounted for in the assimilation equation.
  • A durable, variable speed pump provides air flow through the partitioning valves, followed by the sample and reference IRGAs, with flow rates from 1 to 2.5 liters per minute.

Environmental controls

Automated adjustments of experimental variables combined with stable control of non-experimental parameters allows you to test hypotheses without the risk of confounding factors—only the test parameter changes.

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  • Responsive CO2 control means faster assimilation measurements and enables The Dynamic Assimilation™ Technique.
  • For a CO2 source, it uses common food-grade 8-gram cylinders that are easily available worldwide. One cylinder provides up to 8 hours of CO2 under normal operating conditions.
  • Compatible with tank gases for a CO2 source or custom gas blends.
  • Extended CO2 control range from 0 to 3,100 µmol mol-1 for additional protocols.
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  • Precise water vapor control maintains ideal conditions in the sample chamber. The LI-6800 adjusts quickly to setpoints set manually or with programs.
  • Automatic condensation protection alerts you to risk and overrides setpoints to protect sensitive components.
  • No harmful chemicals for water control. The humidifier column uses Nafion tubes in water to humidify the air stream—just add water. The desiccant column uses indicating silica gel beads to remove water vapor from the air stream.
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  • Control leaf temps up to ±10 °C from ambient with the built-in heat exchanger.
  • Temperature can be controlled at a setpoint, ramp, or computed value to raise or lower sample temperature according to your experimental requirements.
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  • Highly uniform illumination of the sample minimizes artifacts that cause errors in gas exchange measurements and confound the understanding of processes that require comparison of gas exchange and PAM chlorophyll a fluorescence parameters.
  • Ambient light measurements measured by the included LI-190R Quantum Sensor are included in the dataset and used when light sources track ambient.
  • In-chamber light measurement above the leaf ensures leaf illumination at the setpoint.
  • Small and large light sources measure their own output before the chamber to account for losses due to transparent film and other sources of interference to ensure that the leaf is illuminated at the setpoint.

Expandable, extendable, customizable

The LI-6800 is designed to adapt to your experimental needs with a range of customizable features and programming.

Tank adapter kit

For a CO2 supply from tank gases, the Tank Adapter Kit (9968-109) makes it simple to connect a tank of compressed CO2 to the CO2 injector.

Custom air supply

Connect a custom gas blend to the air inlet—either before or after the console pump—for low O2 measurement or other experiments. The hardware is included with the spares kit.

Advanced programming

The LI-6800 is fully configurable—you can create custom configurations with the graphical programming interface on the instrument and write programs from scratch, all in the Python Programming Language. Write complex control algorithms, control peripherals, create custom interface prompts, or keep it simple and customize existing programs to suit your application. Background programs open the full capabilities of the LI-6800 for customization.

Auxiliary peripherals

Add peripheral sensors, mixing fans, and more to the LI-6800. To control peripherals and record their data in with your dataset, the LI-6800 provides the following:

  • Digital inputs and outputs to control and read data from digital devices.
  • Analog inputs and outputs to control and record data from analog sensors.
  • Auxiliary power options—12 V and 5 V from the console and 5 V from the head for mixing fans, pumps, and more.
  • 5 V excitation voltage for active sensors.
  • Auxiliary Power Cable (9968-242) to power the LI-6800 from external DC power, such as a deep cycle battery.


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