Domain: Natural Science — Physics
Target concept: Fluorescence of quinine in tonic water under ultraviolet light compared to visible light

Video generation prompt: A glass of clear tonic water is placed on a dark table, illuminated by a UV flashlight, and then illuminated by a white light flashlight, with the camera kept fixed.

Evaluation guide:
(i) Target concept: UV-induced fluorescence of quinine as a photophysical emission process requiring specific excitation wavelength and immediate cessation.
Minimum mechanism: Quinine molecules must absorb UV photons (not visible light), undergo electronic excitation, and radiatively decay to emit ~450 nm photons; emission must be spatially confined to the liquid phase and temporally locked to UV exposure.
(ii)Storyline: [Phase 1] Static wide shot establishes fixed camera view: dark table, centered clear glass with transparent liquid. [Phase 2] UV flashlight enters frame from off-camera left/right and illuminates glass: immediate onset of blue-white glow *only inside liquid*, no emission from glass or air. [Phase 3] UV flashlight withdraws completely; glow vanishes within one frame. [Phase 4] White flashlight enters same spatial position/orientation and illuminates glass: liquid returns to full transparency, revealing accurate optical properties (refraction, meniscus, surface reflections). [Visibility constraint] All causal transitions (glow onset/offset) must be directly observable without inference; no occlusion, no cutaways, no voiceover explanation; phenomena must be self-evident from image content alone.

Manual:
Experimental Procedure
1. Place a clear glass filled with clear tonic water on a dark, non-reflective table.
2. Illuminate the glass with a handheld UV flashlight (365 nm) — keep camera fixed.
3. Switch illumination to a handheld white light flashlight — keep camera fixed.
Observation of Experimental Phenomena
Under UV light: tonic water emits a bright, uniform blue-white fluorescence visible only within the liquid volume. Under white light: tonic water appears fully transparent with no glow, showing accurate meniscus and surface reflections.
Summary of Experimental Principles
Quinine sulfate in tonic water absorbs ultraviolet photons and re-emits energy as visible blue-white light via fluorescence — a photoluminescent process requiring UV excitation and ceasing instantly upon removal of UV source.

Prompt Grounding rubric:
level_1: No glass of tonic water is shown; no dark table surface appears; neither the UV flashlight nor the white-light flashlight is present; the camera pans, zooms, or repositions instead of holding one fixed view; neither illumination pass (UV or white) is attempted.
level_2: A glass is present but holds an opaque, colored, or empty liquid instead of clear tonic water, or the table is missing or brightly lit instead of dark; only one flashlight (UV or white) appears and is never pointed at the glass, or the second flashlight is entirely absent; the camera reframes or moves between the two illumination attempts.
level_3: A clear glass of tonic water sits on a dark table; both the UV flashlight and the white-light flashlight are visibly present near the glass; the camera holds one fixed framing for the whole sequence; however, one flashlight's beam misses the glass entirely, or the white flashlight is used before the UV flashlight instead of after.
level_4: The clear glass of tonic water, the dark table, the UV flashlight, and the white-light flashlight are all present and correctly placed; the camera stays in its single fixed framing throughout; the UV flashlight is aimed at the glass first, then the white flashlight is aimed at the same glass in the same shot; no substitute props appear (no LED panel standing in for a flashlight, no plastic cup standing in for the glass).
level_5: All required objects are present and rendered as specified: a cylindrical clear glass (not a beaker or tumbler), tonic water with no visible bubbles or sediment, a matte non-reflective dark table, a handheld UV flashlight with a visibly violet-toned beam, and a handheld white-light flashlight with a neutral-white beam (not yellow- or blue-tinted); the UV pass finishes before the white-light pass begins with no overlap between the two; both beams are aimed at the center of the glass; the camera is static, level, front-facing, and centered on the glass with no hands or extra objects intruding into frame.

Scientific and Causal Correctness rubric:
level_1: No fluorescence appears under UV: the liquid looks the same brightness and color under both the UV flashlight and the white flashlight; the tonic water looks dark or gray under UV instead of glowing; there is no blue-white emission at all.
level_2: A glow is present but wrongly attributed: it appears only under the white flashlight instead of the UV flashlight; it looks green, yellow, or red instead of blue-white; the glow seems to come from the table, the flashlight housing, or the surrounding air rather than from inside the liquid; the liquid gets darker instead of brighter under UV; the white-light pass shows an unexplained glow or color shift.
level_3: A blue-white glow appears in the liquid only while the UV flashlight is on and is absent under the white flashlight, but the glow is unsteady - it flickers, fills only part of the liquid, or visibly lingers for a beat after the UV flashlight is switched off (as though phosphorescent rather than fluorescent); or the liquid looks cloudy instead of clear under the white flashlight.
level_4: A blue-white glow fills the liquid's volume every time - and only when - the UV flashlight illuminates it; under the white flashlight the liquid looks fully clear with no glow at all, matching how tonic water actually looks in daylight; no glow leaks from the glass walls, the meniscus, or surface reflections; the glow appears and disappears together with the UV flashlight being switched on and off.
level_5: The glow is bright and evenly spread through the liquid, confined strictly to the liquid itself with no bleed onto the glass walls and no halo around the glass; under the white flashlight the liquid is fully transparent with correct specular highlights and a visible meniscus curve; the color of the glow reads as a clean blue-white throughout - never washed to plain white by overexposure and never shifted toward violet or green - consistent with quinine's characteristic fluorescence.

Spatiotemporal Consistency rubric:
level_1: The glass jumps to a different position or size between frames; the table's surface pattern or color changes without cause; a flashlight vanishes or appears without a hand carrying it into or out of frame; the room lighting switches from bright to dark instantly with no transition; the liquid's fill level changes on its own between shots.
level_2: The glass rotates or tilts between the UV and white-light phases without anyone touching it; the table's ambient brightness changes between phases even though no light source explains it; a flashlight beam's width or angle jumps between frames while the hand holding it stays still; the liquid surface shows ripples in one phase but not the other with no visible disturbance causing them.
level_3: A brief freeze or stutter occurs as the video cuts from the UV phase to the white-light phase; the camera drifts slightly from its starting framing (a small but visible shift, not a full reframing); the shadow cast by the glass changes sharpness between the two phases even though neither flashlight's distance nor angle changed; the glass's reflected highlight brightness differs between phases by more than the change in light source would explain.
level_4: The glass stays in the same position and orientation throughout; the table's surface pattern and shading stay consistent; each flashlight's distance and angle to the glass stay the same across its own phase; the shadow the glass casts keeps a direction and shape that matches the flashlight's position; the liquid surface stays still and undisturbed; no jump cuts, warping, or shape distortion of the glass or table occur.
level_5: Every spatial relationship holds without exception: no mismatched motion blur (e.g., a sharp glass next to a blurred hand in the same frame); the glass and the background table edge shift together with no parallax mismatch if the camera or subject moves at all; brightness stays steady between consecutive frames with no unexplained flicker; each flashlight's beam keeps a continuous shape and edge as it enters and leaves frame, with no sudden pop-in of the beam cone; any reflection on the glass (e.g., of the ceiling or of a flashlight) tracks correctly with viewing angle in both phases.