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TECHNOLOGY 43
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i.e., depth in the wood, while the differences in the spectrum’s In the near-surface layers of the earlywood zone (GOb)
quality result from the wood’s non-uniform structure in the subjected to vacuum impregnation, the higher intensity of
annual growth. carbon signals compared to the latewood zone (GOc) may
Pine is a species characterised by relatively uniform annual result from the stronger interaction of GO with cells in this

growth. However, it should always be considered that the wood zone.
annual growth width is not ideal. The laser beam focus in In the earlywood zone, GO can more easily penetrate the
deeper layers of wood can go beyond the early wood zone conducting cells’ lumen (coils). As shown in previous studies,
and catch the signal from the second zone—latewood. graphene oxide also penetrates the parenchyma cells and
The spectra identified in the plasma radiation generated by resin ducts, which are numerous in pine wood, usually on
the laser beam were dominated by carbon compounds and the border between earlywood and latewood.
impurities containing the elements—magnesium and oxygen. Different results were obtained in the pressureless
In the early control wood (cb), the intensity of the carbon impregnation method using ultrasound than in the vacuum
signal measured during the first four laser pulses was low. impregnation method.

In the wood impregnated with graphene oxide, using the Also, about the control, the results of these studies are
vacuum method (GOb), in this wood zone, the signal intensity fascinating. The carbon signal intensity measured in the near-
measured during the first four laser pulses was between surface layers of the GOUb zone ranged from 3294 to 17,178.
58,087 and 83,916. In short-term pressureless wood impregnation methods,
Large internal spaces and numerous funnel-shaped the agent’s penetration depth may be small. Nevertheless, the
cavities on the wall surface characterise the structure of the penetration parameters depend on many other factors, such
conducting cells in the early wood zone. These cells efficiently as the wood species, its moisture content, and the chemical

conduct liquids during impregnation processes. Additionally, nature of the impregnant.
in vacuum impregnation, impregnants can be sucked deep Low carbon signals in the entire wood zone (GOUb, GOUc)
into these cells. may indicate that GO was not introduced into the interior of
The latewood zone (cc, GOc) is impermeable to liquids, the wood cells.
but the wood cells that make up this zone are characterised Additionally, referring to the results obtained from the
by thick cell walls. tests on control wood samples, it can be assumed that the
In this wood zone, the carbon content from structural ultrasound action causes changes in the near-surface layers
polymers, such as cellulose, hemicelluloses, or lignin, should
be higher than in the earlywood zone, which is especially

visible in the control wood. pixabay.com
The wood cell wall also contains approximately 66 percent
carbon. However, it should be noted that numerous phloem
rays are composed of parenchyma cells containing carbon
compounds in the earlywood and latewood zones. The higher
intensity of carbon signals in the deeper layers of the cb
zone than the cc zone may result from identifying carbon

from cell wall polymers and carbon compounds found in
parenchyma cells.