DIVING-PAM-II Underwater Fluorometer with Miniature Spectrometer

How it works

The DIVING-PAM-II lets you study photosynthesis down to 50 m water depth. The whole instrument is operated through 10 infrared reflection switches placed inside a transparent, cylinder-shaped housing. An energy-saving B/W transflective screen shows instrument status and measured data and stays readable even in sunlight. For long-term assessment of photosynthesis, the instrument can also be run from a computer over a special underwater cable.

The MINI-SPEC miniature spectrometer comes with the basic system and adds a new level of information: it measures PAR spectra, which vary significantly with water depth, and allows spectral analysis of the reflectance and fluorescence emission of a sample. A new internal PAR sensor continuously records the intensity of the internal light source.

Highlights

• Miniature spectrometer for PAR measurement, with spectral information on PAR and reflectance
• Wireless LAN for easy data download at the experimental site
• Low-power transflective B/W screen with graphical and alphanumerical display
• High-power LED for actinic light and saturation pulses, plus a far-red LED for PS I excitation
• Advanced pressure and temperature sensor
• High-capacity battery for more than 1,300 PS II yield measurements
• Flash memory for more than 27,000 saturation pulse analyses
• Continuous monitoring of the internal light intensity by the built-in PAR sensor
• Automatic calculation of all relevant saturation pulse analysis parameters

Basic system

Supplied with 1.5 m flexible fiber optics, miniature spectrometer, distance clip, dark leaf clips, surface holder, PC Interface Box, battery charger, USB cable, 5 m underwater cable and WinControl-3 software, all in a rugged outdoor transport case. In dry environments, MINI-PAM-II fluorometer accessories can be used together with the DIVING-PAM-II.

Blue and red versions: DIVING-PAM-II/B and DIVING-PAM-II/R

The two versions differ in the color of the primary LED. The blue version (DIVING-PAM-II/B) has a blue LED peaking at about 475 nm; in the red version (DIVING-PAM-II/R) it is replaced by a red LED peaking at about 655 nm. Both carry a second, far-red LED that emits maximally above 700 nm for specific excitation of photosystem I.

The spectral window for fluorescence detection also differs: the blue version detects fluorescence at wavelengths > 630 nm, the red version at wavelengths > 700 nm.

Blue or red?

• Sensitivity: its wider detection range makes the blue version more sensitive. In samples rich in chlorophyll, however, much of the short-wavelength fluorescence it could pick up is reabsorbed by chlorophyll, so its advantage becomes small.
• Cyanobacteria: they often absorb blue light poorly, so the red version is usually preferred for cyanobacteria studies; the blue version gives a low signal-to-noise ratio with them.
• LHC II excitation: blue actinic light excites the broad short-wavelength band of the main light-harvesting complex of photosystem II in higher plants and green algae (LHC II), while red light excites its long-wavelength band. If LHC II excitation matters, the blue version may be the better choice.
• Blue-light photoreceptors: blue light is absorbed by photoreceptors that can trigger responses such as chloroplast relocation in higher plants, which can affect the fluorescence signal by changing light efficiency.