Domain: Natural Science — Environmental Science
Target concept: Benzo[a]pyrene Detection (Fluorescence Method)

Video generation prompt: Take 1 mL of the extracted water sample and place it into a quartz cuvette. Position the cuvette under a fluorescence spectrophotometer with an excitation wavelength of 365 nm.

Evaluation guide:
(i) Target concept: Fluorescence-based detection of benzo[a]pyrene via UV excitation at 365 nm in aqueous extract.
Minimum mechanism: Presence of benzo[a]pyrene in solution → absorption of 365 nm photons → electronic excitation → radiative relaxation → emission of longer-wavelength blue to blue-violet photons (roughly 400-430 nm, not blue-green); requires transparent quartz (not glass) to transmit 365 nm UV and avoid quenching.
(ii)Storyline: Frame 1–2: Hand holds quartz cuvette; clear liquid inside visible. Frame 3–4: Hand moves cuvette toward spectrophotometer stage. Frame 5–6: Cuvette settles onto stage with upright orientation; excitation source (violet-UV) becomes active and illuminates cuvette face. Frame 7–8: A blue/blue-violet fluorescence glow emerges within the liquid volume, spatially confined and co-located with the excitation spot. Frame 9–10: Excitation deactivates → fluorescence fades out promptly; cuvette remains stationary, liquid surface undisturbed. Perspective: Fixed frontal close-up (cuvette center-frame), shallow depth of field emphasizing liquid volume; no cutaways or POV shifts.

Manual:
Experimental Procedure
1. Take 1 mL extracted water sample.
2. Transfer into quartz cuvette.
3. Place cuvette onto fluorescence spectrophotometer sample stage.
4. Activate 365 nm excitation source aligned with cuvette.
Observation of Experimental Phenomena
Blue (blue-violet) fluorescence emission appears within the liquid volume during 365 nm excitation and fades out once excitation stops.
Summary of Experimental Principles
Benzo[a]pyrene absorbs 365 nm UV light and re-emits energy as visible blue to blue-violet fluorescence (~400-430 nm) — enabling selective detection in water samples via fluorescence spectroscopy.

Prompt Grounding rubric:
level_1: No quartz cuvette appears, no water sample is visible inside it, no fluorescence spectrophotometer is shown, and no action of placing or positioning the cuvette takes place.
level_2: A quartz cuvette is shown, but empty; or the water sample is held in a different kind of container (a glass vial, a plastic tube) instead of a quartz cuvette; the spectrophotometer is only partly visible and not oriented to receive the cuvette; and no placement action is shown.
level_3: The quartz cuvette holds liquid, filling roughly a quarter to a third of its height (the exact 1 mL volume needn't be readable); the cuvette sits on or near the spectrophotometer's sample stage; and a UV excitation source, labeled 365 nm or recognizable as a UV lamp/LED, is visible nearby, even if its alignment with the cuvette isn't yet confirmed.
level_4: Everything at the 3-point level holds, and in addition the cuvette clearly contains a colorless liquid, sits correctly seated on the sample stage, the UV excitation source (marked or visually distinct as 365 nm/UV) is positioned with a direct line of sight to the cuvette, and the full placement action is shown, from a hand approaching the cuvette to it coming to rest in position.
level_5: Everything at the 4-point level holds, and in addition there is exactly one quartz cuvette, containing a colorless, transparent liquid consistent with an extracted water sample, seated on the spectrophotometer stage, with the excitation source explicitly labeled '365 nm' or emitting a visible violet-UV glow at the cuvette face, no extra containers/tools/labels in the frame, and the action reads simply as: hand picks up the cuvette, positions it on the stage, and stops with it centered and upright.

Scientific and Causal Correctness rubric:
level_1: The liquid fluoresces under light that clearly isn't 365 nm (ordinary white light, or an obviously different color like 450 nm blue), or no fluorescence appears at all despite a correctly set-up cuvette and lamp, or the liquid itself looks turbid, yellow, or brown (signs of contamination rather than a clean water extract).
level_2: The liquid in the cuvette is visibly colored (yellow, amber) or cloudy rather than clear; fluorescence is absent, or only appears under ordinary room light rather than the UV source; there is no visible causal link between turning on the 365 nm excitation and any glow appearing.
level_3: The liquid is colorless and clear; the excitation source emits a visibly violet-UV light distinct from white or blue light; a faint or spatially limited glow appears only while the UV source is on and aimed at the cuvette, but the glow's color doesn't clearly read as blue/blue-violet: for example it looks white, red, or like a dim colorless haze.
level_4: Everything at the 3-point level holds, and in addition the fluorescence reads as a blue or blue-violet glow that appears only within the liquid inside the cuvette while the UV source is active, and disappears essentially as soon as the source is switched off, staying confined to the liquid without spilling visibly onto the cuvette walls or the stage behind it.
level_5: Everything at the 4-point level holds, and in addition the glow only ever appears while the 365 nm source is on and properly aimed, it is bright, spatially confined to the liquid, and distinctly blue/blue-violet rather than white, yellow, or purple, it stops within roughly a frame of the source turning off, there is no stray glow from the cuvette walls or surrounding air, and there is no lingering glow or reflection after the light turns off that could be mistaken for fluorescence.

Spatiotemporal Consistency rubric:
level_1: The cuvette jumps directly onto the stage with no travel shown, the liquid appears or disappears mid-sequence, the lighting switches from ordinary room light to UV with no transition, the cuvette rotates by more than 90 degrees with no visible motion in between, or the stage/instrument's shape changes across frames.
level_2: The cuvette flickers out of view for two or more consecutive frames, the liquid's level or shape changes abruptly without cause, the UV source switches on or off with a visible jump rather than a continuous transition, or the hand's motion looks like it teleports between its starting, middle, and ending positions.
level_3: The cuvette stays put once placed; the liquid surface is calm and unrippled; the UV source stays lit continuously through the observation phase; the hand's motion looks smooth and physically reasonable, with no sudden unexplained speed changes; and there is no clipping, warping, or occlusion glitch involving the cuvette or hand.
level_4: Everything at the 3-point level holds, and in addition the whole hand motion reads as one continuous, natural gesture (approaching, making contact, gently setting the cuvette down, releasing, and pulling back) without freezing or stutter; the room's ambient lighting stays constant, the violet-UV glow from the source doesn't flicker in brightness, and the cuvette holds the same orientation and position throughout.
level_5: Everything at the 4-point level holds, and in addition there is no visible jump in any object's position, scale, or rotation from one frame to the next, the liquid's meniscus stays essentially still with a consistent curve, any shadow cast by the hand or cuvette shifts smoothly and matches the light's apparent direction, there is no blur or double-imaging that obscures what's being shown, and the camera viewpoint never pans, tilts, or zooms.